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Math Formulae Page: 440 K-12 Formulas

A complete K-12 math formulae reference with 440 formulas across arithmetic, algebra, geometry, trigonometry, statistics, finance math, matrices, vectors, sets, and AP or IB calculus readiness.

Published: May 17, 2026Updated: May 17, 2026
Math Formulae Page: 440 K-12 Formulas feature image

Guide Oversight & Review Policy

CalculatorWallah guides are written to explain calculator assumptions, source limitations, and when users should move from a rough estimate to an official rule, institution policy, or clinician conversation.

Reviewed by Jitendra Kumar, Founder & Editorial Standards Lead. Page updated May 17, 2026. Trust-critical pages are reviewed when official rates or rules change. Evergreen calculator guides are checked on a recurring quarterly or annual cycle depending on topic volatility. Topic ownership: Sales tax and tax-sensitive estimate tools, Education and GPA planning calculators, Health, protein, and screening-formula pages, Platform-wide publishing standards and methodology.

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On This Page

Overview

This math formulae page turns the uploaded K-12 checklist into a complete reference: 440 formula entries across 26 topics. It starts with number sense, fractions, ratios, exponents, and algebra, then moves into coordinate geometry, 2D and 3D geometry, trigonometry, statistics, financial mathematics, matrices, vectors, logic, and calculus readiness.

The goal is not to make students memorize a wall of symbols. A formula page is useful when it helps you identify the right relationship, check units, substitute values carefully, and decide whether a calculator or graphing step should come next. For formula-heavy solving, pair this reference with the Math Equation Solver, Scientific Calculator, and topic-specific tools in the Math Calculators hub.

How To Use This Page

Start with the topic, not the formula name. If the problem is about a triangle, go to the triangle section before searching for an equation. If it is about a sequence, decide whether the pattern is arithmetic, geometric, recursive, finite, or infinite before substituting numbers.

Then read the "Use" column. Similar-looking formulas often answer different questions: circumference is distance around a circle, circle area is space inside the circle, arc length is part of the circumference, and sector area is part of the circle's area. In algebra, slope, average rate of change, secant slope, and difference quotient all look related, but they sit at different levels of precision.

Finally, check restrictions. Denominators cannot be zero, logarithm inputs must be positive, inverse functions require one-to-one behavior, geometric infinite series need |r| < 1, and many geometry formulas assume matching units. The table keeps those conditions short so the formula remains scannable. Each row also includes a variables/notation column so the symbols are defined beside the MathJax-rendered formula.

Educational Video

I looked for a credible supporting video from an educational or institutional source rather than embedding a random creator video. A suitable Khan Academy video exists for the foundation behind many geometry formulas, so it is embedded here as context before the complete formula list.

This Khan Academy video is relevant because it shows how formulas start from meaning: perimeter as distance around a shape and area as covered space. That context matters before students jump into the full formula table below.

Formula Index

1. Number Sense & Arithmetic (30 formulae)

#Formula nameFormula or ruleVariables / notationUse
1Place value formula
\[N=\sum_{i=0}^{k}d_i\times10^i\]
\(N\):
total count, population size, or original number
\(d\):
distance, diameter, divisor, or common difference
\(i\):
index value or matrix row index
Break a number into digit values by powers of 10.
2Expanded form formula
\[N=a_n10^n+\cdots+a_1\cdot10+a_0\]
\(a_n\):
nth term of a sequence
\(a_1\):
first term of a sequence
\(N\):
total count, population size, or original number
\(a\):
a known number, coefficient, side length, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Write a number as the sum of its place-value parts.
3Standard form formula
\[N=\sum \text{place values}\]
\(N\):
total count, population size, or original number
Combine expanded place values into one ordinary numeral.
4Rounding rule
\[\begin{gathered}\text{next digit >= 5 -> round up}\\\text{next digit < 5 -> keep}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Round a value to a selected place.
5Absolute value formula
\[|x|=\begin{cases}x,&x\ge0\\-x,&x<0\end{cases}\]
\(x\):
unknown, input variable, or x-coordinate
Find distance from zero without sign direction.
6Additive inverse formula
\[a + (-a) = 0\]
\(a\):
a known number, coefficient, side length, or constant
Find the number that cancels a value under addition.
7Multiplicative inverse formula
\[a\times\frac{1}{a}=1,\quad a\ne0\]
\(a\):
a known number, coefficient, side length, or constant
Find the reciprocal that cancels a value under multiplication.
8Order of operations rule
\[\begin{gathered}\text{Parentheses -> exponents -> multiply/divide -> add/subtract}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Evaluate expressions in the standard order.
9Fraction addition formula
\[\frac{a}{b}+\frac{c}{d}=\frac{ad+bc}{bd}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
Add fractions with unlike denominators.
10Fraction subtraction formula
\[\frac{a}{b}-\frac{c}{d}=\frac{ad-bc}{bd}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
Subtract fractions with unlike denominators.
11Fraction multiplication formula
\[\frac{a}{b}\times\frac{c}{d}=\frac{ac}{bd}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
Multiply numerators and denominators.
12Fraction division formula
\[\frac{a/b}{c/d}=\frac{ad}{bc}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
Divide by multiplying by the reciprocal.
13Mixed number to improper fraction formula
\[a\frac{b}{c}=\frac{ac+b}{c}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
Convert a whole-number-plus-fraction into one fraction.
14Improper fraction to mixed number formula
\[\frac{a}{b}=q+\frac{r}{b},\quad a=bq+r\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(q\):
quotient, probability of failure, or integer part
\(r\):
radius, rate, ratio, remainder, or root
Separate an improper fraction into whole part and remainder.
15Equivalent fractions formula
\[\frac{a}{b}=\frac{ak}{bk},\quad k\ne0\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(k\):
constant, scale factor, index, or number of successes
Create equal fractions by scaling numerator and denominator.
16Simplifying fractions formula
\[\frac{a}{b}=\frac{a/g}{b/g},\quad g=\gcd(a,b)\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(g\):
function g, greatest common factor, or gravitational/constant term
Reduce a fraction to lowest terms.
17Decimal to fraction conversion formula
\[\text{decimal}=\frac{\text{integer}}{10^n}\]
\(n\):
number of terms, sides, observations, trials, or periods
Convert a terminating decimal with n decimal places to a fraction.
18Fraction to decimal conversion formula
\[a/b = a รท b\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
Convert a fraction by dividing numerator by denominator.
19Percent to decimal conversion formula
\[p\%=\frac{p}{100}\]
\(p\):
rate, probability, or focus distance
Turn a percent into a decimal multiplier.
20Decimal to percent conversion formula
\[\text{percent}=100\times\text{decimal}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Turn a decimal into a percent.
21Fraction to percent conversion formula
\[\frac{a}{b}\times100\%\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
Convert a fraction into a percent.
22Percent of a number formula
\[\text{part}=\frac{p}{100}\times\text{whole}\]
\(p\):
rate, probability, or focus distance
Find p percent of a quantity.
23Percent increase formula
\[\text{new}=\text{original}\times\left(1+\frac{p}{100}\right)\]
\(p\):
rate, probability, or focus distance
Increase a value by p percent.
24Percent decrease formula
\[\text{new}=\text{original}\times\left(1-\frac{p}{100}\right)\]
\(p\):
rate, probability, or focus distance
Decrease a value by p percent.
25Percent change formula
\[\text{percent change}=\frac{\text{new}-\text{old}}{\text{old}}\times100\%\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Measure relative change from an original value.
26Ratio formula
\[a:b = a / b\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
Compare two quantities by division.
27Proportion formula
\[\frac{a}{b}=\frac{c}{d}\Longrightarrow ad=bc\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
Solve equal-ratio problems by cross multiplication.
28Unit rate formula
\[\text{unit rate}=\frac{\text{quantity}}{1\ \text{unit}}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Express a rate per one unit.
29Average rate formula
\[\text{average rate}=\frac{\text{total change}}{\text{total time}}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Find one constant rate over an interval.
30Scale factor formula
\[\text{scale factor}=\frac{\text{new length}}{\text{original length}}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Compare similar figures or resized quantities.

2. Factors, Multiples & Number Theory (19 formulae)

#Formula nameFormula or ruleVariables / notationUse
31Divisibility rules
\[\begin{gathered}\text{n is divisible by d if n mod d = 0}\end{gathered}\]
\(d\):
distance, diameter, divisor, or common difference
\(n\):
number of terms, sides, observations, trials, or periods
Rule:
Read the text condition before applying the symbols or calculator workflow.
Test whether division leaves no remainder.
32Factor formula
\[n=a\times b\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Identify numbers that multiply to make n.
33Multiple formula
\[m=k\times n\]
\(k\):
constant, scale factor, index, or number of successes
\(m\):
mass, slope, index, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Generate multiples of a number.
34Prime factorization formula
\[n = p_1^{a} p_2^{b} ...\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(n\):
number of terms, sides, observations, trials, or periods
\(p\):
rate, probability, or focus distance
Write a number as powers of primes.
35Greatest common factor formula
\[\begin{gathered}\text{gcf = product of common primes with smaller exponents}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Find the largest shared factor.
36Least common multiple formula
\[\operatorname{lcm}(a,b)=\frac{|ab|}{\gcd(a,b)}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
Find the smallest shared multiple.
37Euclidean algorithm formula
\[\gcd(a,b)=\gcd(b,a\bmod b)\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
Find a GCF by repeated remainders.
38Exponent rules
\[a^m a^n=a^{m+n},\quad (a^m)^n=a^{mn}\]
\(a\):
a known number, coefficient, side length, or constant
\(m\):
mass, slope, index, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Simplify powers with the same base.
39Product of powers rule
\[a^m\times a^n=a^{m+n}\]
\(a\):
a known number, coefficient, side length, or constant
\(m\):
mass, slope, index, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Multiply powers with the same base.
40Quotient of powers rule
\[\frac{a^m}{a^n}=a^{m-n},\quad a\ne0\]
\(a\):
a known number, coefficient, side length, or constant
\(m\):
mass, slope, index, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Divide powers with the same base.
41Power of a power rule
\[(a^m)^n=a^{mn}\]
\(a\):
a known number, coefficient, side length, or constant
\(m\):
mass, slope, index, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Raise one power to another power.
42Power of a product rule
\[(ab)^n=a^n b^n\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Distribute an exponent across multiplication.
43Power of a quotient rule
\[\left(\frac{a}{b}\right)^n=\frac{a^n}{b^n},\quad b\ne0\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Distribute an exponent across division.
44Zero exponent rule
\[a^0=1,\quad a\ne0\]
\(a\):
a known number, coefficient, side length, or constant
Simplify any nonzero base raised to zero.
45Negative exponent rule
\[a^{-n}=\frac{1}{a^n},\quad a\ne0\]
\(a\):
a known number, coefficient, side length, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Rewrite negative exponents as reciprocals.
46Scientific notation formula
\[N=a\times10^n,\quad 1\le |a|<10\]
\(N\):
total count, population size, or original number
\(a\):
a known number, coefficient, side length, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Write very large or small numbers compactly.
47Standard form to scientific notation formula
\[\text{move decimal }k\text{ places}\to a\times10^k\]
\(a\):
a known number, coefficient, side length, or constant
\(k\):
constant, scale factor, index, or number of successes
Convert an ordinary number to scientific notation.
48Scientific notation multiplication rule
\[(a\times10^m)(b\times10^n)=ab\times10^{m+n}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(m\):
mass, slope, index, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Multiply numbers written in scientific notation.
49Scientific notation division rule
\[\frac{a\times10^m}{b\times10^n}=\frac{a}{b}\times10^{m-n}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(m\):
mass, slope, index, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Divide numbers written in scientific notation.

3. Integers & Rational Numbers (12 formulae)

#Formula nameFormula or ruleVariables / notationUse
50Integer addition rule
\[\begin{gathered}\text{same signs: add absolute values}\\\text{different signs: subtract absolute values}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Add signed whole numbers.
51Integer subtraction rule
\[a - b = a + (-b)\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
Turn subtraction into adding the opposite.
52Integer multiplication rule
\[\begin{gathered}\text{(+)(+) = +, (-)(-) = +, (+)(-) = -}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Choose the sign when multiplying integers.
53Integer division rule
\[\begin{gathered}\text{same signs -> positive}\\\text{different signs -> negative}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Choose the sign when dividing integers.
54Rational number addition formula
\[\frac{a}{b}+\frac{c}{d}=\frac{ad+bc}{bd}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
Add rational numbers as fractions.
55Rational number subtraction formula
\[\frac{a}{b}-\frac{c}{d}=\frac{ad-bc}{bd}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
Subtract rational numbers as fractions.
56Rational number multiplication formula
\[\frac{a}{b}\times\frac{c}{d}=\frac{ac}{bd}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
Multiply rational numbers.
57Rational number division formula
\[\frac{a/b}{c/d}=\frac{ad}{bc},\quad c\ne0\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
Divide rational numbers.
58Comparing rational numbers formula
\[a/b ? c/d by comparing ad ? bc\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
Compare fractions with positive denominators.
59Ordering rational numbers rule
\[\begin{gathered}\text{use common denominators or decimal values}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Place rational numbers from least to greatest.
60Opposite numbers formula
\[a + (-a) = 0\]
\(a\):
a known number, coefficient, side length, or constant
Pair a number with its additive inverse.
61Reciprocal formula
\[reciprocal of a = 1/a, a \ne 0\]
\(a\):
a known number, coefficient, side length, or constant
Find the multiplicative inverse.

4. Algebra Basics (13 formulae)

#Formula nameFormula or ruleVariables / notationUse
62Variable expression formula
\[\begin{gathered}\text{expression value = expression after substituting variables}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Represent unknown quantities with letters.
63Algebraic expression evaluation formula
\[\begin{gathered}\text{if x = a, replace x with a and simplify}\end{gathered}\]
\(a\):
a known number, coefficient, side length, or constant
Evaluate an expression for given values.
64Combining like terms rule
\[\begin{gathered}\text{ax + bx = (a + b)x}\end{gathered}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(x\):
unknown, input variable, or x-coordinate
Combine terms with the same variable part.
65Distributive property formula
\[a(b + c) = ab + ac\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
Multiply across a sum or difference.
66Factoring common factor formula
\[ab + ac = a(b + c)\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
Pull out a shared factor.
67One-step equation formula
\[x+a=b\Longrightarrow x=b-a,\quad ax=b\Longrightarrow x=\frac{b}{a}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(x\):
unknown, input variable, or x-coordinate
Undo one operation to solve.
68Two-step equation formula
\[ax+b=c\Longrightarrow x=\frac{c-b}{a}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
Undo addition/subtraction, then multiplication/division.
69Multi-step equation formula
\[\begin{gathered}\text{simplify both sides, then isolate x}\end{gathered}\]
\(x\):
unknown, input variable, or x-coordinate
Solve equations with combining, distributing, or repeated operations.
70Literal equation rearrangement formula
\[\begin{gathered}\text{solve for target variable using inverse operations}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Rearrange formulas for a different variable.
71Inequality solving rule
\[\begin{gathered}\text{multiply/divide by a negative -> reverse inequality sign}\end{gathered}\]
\(a\):
a known number, coefficient, side length, or constant
Solve inequalities without losing order direction.
72Compound inequality formula
\[\begin{gathered}\text{a < x < b or x < a OR x > b}\end{gathered}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
Solve "and" and "or" inequality statements.
73Absolute value equation formula
\[|x-a|=b\Longrightarrow x=a\pm b,\quad b\ge0\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(x\):
unknown, input variable, or x-coordinate
Solve equations involving distance from a center.
74Absolute value inequality formula
\[\begin{gathered}|x-a|<b\Longrightarrow a-b<x<a+b\\|x-a|>b\Longrightarrow x<a-b\ \text{or}\ x>a+b\end{gathered}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(x\):
unknown, input variable, or x-coordinate
Solve distance-bounded inequalities.

5. Linear Equations & Functions (18 formulae)

#Formula nameFormula or ruleVariables / notationUse
75Slope formula
\[m=\frac{y_2-y_1}{x_2-x_1}\]
\(x_1\):
x-1 coordinate of a point
\(x_2\):
x-2 coordinate of a point
\(y_1\):
y-1 coordinate of a point
\(y_2\):
y-2 coordinate of a point
\(m\):
slope
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Find steepness from two points.
76Slope-intercept form
\[y=mx+b\]
\(b\):
b known number, coefficient, side length, or constant
\(y\):
dependent variable, output, or y-coordinate
Write a line using slope and y-intercept.
77Point-slope form
\[y-y_1=m(x-x_1)\]
\(x_1\):
x-1 coordinate of a point
\(y_1\):
y-1 coordinate of a point
\(m\):
slope
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Write a line from one point and slope.
78Standard form of a line
\[Ax + By = C\]
\(C\):
constant, coefficient, circumference, or third event as used in the row
Write a line with x and y terms on one side.
79Two-point form of a line
\[y-y_1=\frac{y_2-y_1}{x_2-x_1}(x-x_1)\]
\(x_1\):
x-1 coordinate of a point
\(x_2\):
x-2 coordinate of a point
\(y_1\):
y-1 coordinate of a point
\(y_2\):
y-2 coordinate of a point
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Write a line through two known points.
80Horizontal line formula
\[y = c\]
\(c\):
c known number, coefficient, side length, or constant
\(y\):
dependent variable, output, or y-coordinate
Represent a line with zero slope.
81Vertical line formula
\[x = c\]
\(c\):
c known number, coefficient, side length, or constant
\(x\):
unknown, input variable, or x-coordinate
Represent a line with undefined slope.
82Parallel lines slope rule
\[m1 = m2\]
\(m\):
slope
Check whether nonvertical lines are parallel.
83Perpendicular lines slope rule
\[m_1m_2=-1\]
\(m\):
slope
Check whether nonvertical lines meet at right angles.
84x-intercept formula
\[\begin{gathered}\text{set y = 0 and solve for x}\end{gathered}\]
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Find where a graph crosses the x-axis.
85y-intercept formula
\[\begin{gathered}\text{set x = 0 and solve for y}\end{gathered}\]
\(y\):
dependent variable, output, or y-coordinate
Find where a graph crosses the y-axis.
86Linear function formula
\[f(x) = mx + b\]
\(b\):
b known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
Model constant rate of change.
87Direct variation formula
\[y = kx\]
\(y\):
dependent variable, output, or y-coordinate
Model proportional relationships.
88Inverse variation formula
\[y = k/x\]
\(k\):
constant, scale factor, index, or number of successes
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Model relationships where product xy is constant.
89Constant rate of change formula
\[\begin{gathered}\text{rate = Delta y / Delta x}\end{gathered}\]
\(\Delta x\):
width of each subinterval or change in x
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Measure equal change per input unit.
90Arithmetic sequence formula
\[a_n=a_1+(n-1)d\]
\(a_n\):
nth term of a sequence
\(a_1\):
first term of a sequence
\(a\):
a known number, coefficient, side length, or constant
\(d\):
common difference
\(n\):
number of terms, sides, observations, trials, or periods
Find the nth term of a linear sequence.
91Arithmetic series formula
\[S_n=\frac{n}{2}(a_1+a_n)\]
\(a_n\):
nth term of a sequence
\(a_1\):
first term of a sequence
\(S\):
sum, series total, sale price, or named set S
\(a\):
a known number, coefficient, side length, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Sum the first n terms of an arithmetic sequence.
92Linear interpolation formula
\[y=y_1+\frac{(x-x_1)(y_2-y_1)}{x_2-x_1}\]
\(x_1\):
x-1 coordinate of a point
\(x_2\):
x-2 coordinate of a point
\(y_1\):
y-1 coordinate of a point
\(y_2\):
y-2 coordinate of a point
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Estimate between two known points on a line.

6. Systems of Equations (9 formulae)

#Formula nameFormula or ruleVariables / notationUse
93System of linear equations formula
\[a1x + b1y = c1; a2x + b2y = c2\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Represent two linear equations solved together.
94Substitution method formula
\[\begin{gathered}\text{solve one equation for a variable, then substitute into the other}\end{gathered}\]
\(a\):
a known number, coefficient, side length, or constant
Solve a system by replacing a variable expression.
95Elimination method formula
\[\begin{gathered}\text{multiply equations so one variable cancels when added/subtracted}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Solve a system by removing one variable.
96Graphing method rule
\[\begin{gathered}\text{solution = intersection point(s)}\end{gathered}\]
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
Rule:
Read the text condition before applying the symbols or calculator workflow.
Solve a system by graphing.
97Determinant formula for 2x2 systems
\[D = ad - bc\]
\(D\):
determinant
Compute the determinant of [[a,b],[c,d]].
98Cramer's rule for 2x2 systems
\[x=\frac{D_x}{D},\quad y=\frac{D_y}{D}\]
\(D_x\):
determinant after replacing the matching variable column
\(D_y\):
determinant after replacing the matching variable column
\(D\):
determinant
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Solve a 2-variable system using determinants.
99Cramer's rule for 3x3 systems
\[x_i = \det(A_i) / \det(A)\]
\(x_i\):
ith data value or sample value
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(i\):
index value or matrix row index
\(x\):
unknown, input variable, or x-coordinate
Solve a 3-variable system using determinant replacement.
100Matrix equation formula
\[Ax = b\]
\(b\):
b known number, coefficient, side length, or constant
Write a linear system in matrix form.
101Matrix inverse solution formula
\[x = A^(-1)b\]
\(A\):
matrix or first event, depending on the row
\(b\):
b known number, coefficient, side length, or constant
\(x\):
unknown, input variable, or x-coordinate
Solve an invertible matrix equation.

7. Exponents, Radicals & Roots (11 formulae)

#Formula nameFormula or ruleVariables / notationUse
102Square root formula
\[\sqrt{x}=y\Longleftrightarrow y^2=x,\ y\ge0\]
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Find the principal square root.
103Cube root formula
\[\sqrt[3]{x}=y\Longleftrightarrow y^3=x\]
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Find the number whose cube is x.
104nth root formula
\[\sqrt[n]{x}=x^{1/n}\]
\(n\):
number of terms, sides, observations, trials, or periods
\(x\):
unknown, input variable, or x-coordinate
Rewrite roots as fractional exponents.
105Radical simplification formula
\[\sqrt{ab} = \sqrt{a}\sqrt{b}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
Separate perfect-square factors.
106Radical multiplication rule
\[\sqrt{a}\sqrt{b} = \sqrt{ab}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
Multiply compatible radicals.
107Radical division rule
\[\sqrt{a}/\sqrt{b} = \sqrt{a/b}, b > 0\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
Divide compatible radicals.
108Rational exponent formula
\[a^(m/n) = \sqrt[n]{a^{m}}\]
\(a\):
a known number, coefficient, side length, or constant
\(m\):
mass, slope, index, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Connect exponents and roots.
109Converting radicals to rational exponents
\[\sqrt[n]{a^{m}} = a^(m/n)\]
\(a\):
a known number, coefficient, side length, or constant
\(m\):
mass, slope, index, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Rewrite radical notation as exponent notation.
110Converting rational exponents to radicals
\[a^(m/n) = \sqrt[n]{a^{m}}\]
\(a\):
a known number, coefficient, side length, or constant
\(m\):
mass, slope, index, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Rewrite exponent notation as radical notation.
111Square root property
\[x^2=a\Longrightarrow x=\pm\sqrt{a}\]
\(a\):
a known number, coefficient, side length, or constant
\(x\):
unknown, input variable, or x-coordinate
Solve quadratic equations that are perfect squares.
112Distance using square roots formula
\[d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\]
\(x_1\):
x-1 coordinate of a point
\(x_2\):
x-2 coordinate of a point
\(y_1\):
y-1 coordinate of a point
\(y_2\):
y-2 coordinate of a point
\(d\):
distance, diameter, divisor, or common difference
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Use the Pythagorean theorem on coordinate differences.

8. Polynomials (17 formulae)

#Formula nameFormula or ruleVariables / notationUse
113Polynomial degree rule
\[\begin{gathered}\text{degree = highest exponent with nonzero coefficient}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Identify polynomial degree.
114Polynomial addition rule
\[(\sum a_i x^{i}) + (\sum b_i x^{i}) = \sum(a_i + b_i)x^{i}\]
\(a_i\):
ith term or indexed value
\(a\):
a coefficient in the polynomial or quadratic
\(b\):
b coefficient in the polynomial or quadratic
\(i\):
index value or matrix row index
\(x\):
unknown, input variable, or x-coordinate
Add like polynomial terms.
115Polynomial subtraction rule
\[P(x) - Q(x) = P(x) + (-Q(x))\]
\(P\):
principal, perimeter, probability, or point P as used in the row
\(Q\):
quartile, matrix quotient, or named quantity Q
\(x\):
unknown, input variable, or x-coordinate
Subtract by distributing the negative.
116Polynomial multiplication rule
\[(\sum a_i x^{i})(\sum b_j x^{j}) = \sum a_i b_j x^(i+j)\]
\(a_i\):
ith term or indexed value
\(a\):
a coefficient in the polynomial or quadratic
\(b\):
b coefficient in the polynomial or quadratic
\(i\):
index value or matrix row index
\(j\):
index value or matrix column index
\(x\):
unknown, input variable, or x-coordinate
Multiply every term by every term.
117Monomial multiplication formula
\[(ax^{m})(bx^{n}) = ab x^(m+n)\]
\(m\):
mass, slope, index, or constant
\(n\):
number of terms, sides, observations, trials, or periods
\(x\):
unknown, input variable, or x-coordinate
Multiply one-term expressions.
118Binomial multiplication formula
\[(a + b)(c + d) = ac + ad + bc + bd\]
\(a\):
a coefficient in the polynomial or quadratic
\(b\):
b coefficient in the polynomial or quadratic
\(c\):
c coefficient in the polynomial or quadratic
\(d\):
distance, diameter, divisor, or common difference
Multiply two binomials.
119FOIL formula
\[(a + b)(c + d) = ac + ad + bc + bd\]
\(a\):
a coefficient in the polynomial or quadratic
\(b\):
b coefficient in the polynomial or quadratic
\(c\):
c coefficient in the polynomial or quadratic
\(d\):
distance, diameter, divisor, or common difference
Use first, outer, inner, last for binomials.
120Special product: square of a binomial
\[(a\pm b)^2=a^2\pm2ab+b^2\]
\(a\):
a coefficient in the polynomial or quadratic
\(b\):
b coefficient in the polynomial or quadratic
Expand a binomial square.
121Special product: difference of squares
\[(a-b)(a+b)=a^2-b^2\]
\(a\):
a coefficient in the polynomial or quadratic
\(b\):
b coefficient in the polynomial or quadratic
Factor or expand conjugates.
122Special product: sum of cubes
\[a^3+b^3=(a+b)(a^2-ab+b^2)\]
\(a\):
a coefficient in the polynomial or quadratic
\(b\):
b coefficient in the polynomial or quadratic
Factor a sum of cubes.
123Special product: difference of cubes
\[a^3-b^3=(a-b)(a^2+ab+b^2)\]
\(a\):
a coefficient in the polynomial or quadratic
\(b\):
b coefficient in the polynomial or quadratic
Factor a difference of cubes.
124Factoring trinomials formula
\[x^{2} + bx + c = (x + m)(x + n), m + n = b, mn = c\]
\(b\):
b coefficient in the polynomial or quadratic
\(c\):
c coefficient in the polynomial or quadratic
\(m\):
mass, slope, index, or constant
\(n\):
number of terms, sides, observations, trials, or periods
\(x\):
unknown, input variable, or x-coordinate
Factor simple quadratic trinomials.
125Factoring by grouping formula
\[ax + ay + bx + by = (a + b)(x + y)\]
\(a\):
a coefficient in the polynomial or quadratic
\(b\):
b coefficient in the polynomial or quadratic
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Factor four-term expressions by pairs.
126Remainder theorem
\[\begin{gathered}\text{remainder when P(x) is divided by x - a is P(a)}\end{gathered}\]
\(P\):
principal, perimeter, probability, or point P as used in the row
\(a\):
a coefficient in the polynomial or quadratic
\(x\):
unknown, input variable, or x-coordinate
Find a division remainder without dividing.
127Factor theorem
\[x - a is a factor of P(x) \Longleftrightarrow P(a) = 0\]
\(P\):
principal, perimeter, probability, or point P as used in the row
\(a\):
a coefficient in the polynomial or quadratic
\(x\):
unknown, input variable, or x-coordinate
Connect zeros and linear factors.
128Polynomial long division formula
\[P(x) = D(x)Q(x) + R(x)\]
\(D\):
difference, determinant, diameter, or named constant D
\(P\):
principal, perimeter, probability, or point P as used in the row
\(Q\):
quartile, matrix quotient, or named quantity Q
\(R\):
radius, right sum, range endpoint, or outer radius
\(x\):
unknown, input variable, or x-coordinate
Divide polynomials with quotient and remainder.
129Synthetic division formula
\[\begin{gathered}\text{use coefficients with root a for divisor x - a}\end{gathered}\]
\(a\):
a coefficient in the polynomial or quadratic
Shortcut division by a linear divisor.

9. Quadratic Equations & Functions (14 formulae)

#Formula nameFormula or ruleVariables / notationUse
130Standard form of a quadratic
\[y = ax^{2} + bx + c\]
\(c\):
c coefficient in the polynomial or quadratic
\(y\):
dependent variable, output, or y-coordinate
Write a quadratic by coefficients.
131Vertex form of a quadratic
\[y = a(x - h)^{2} + k\]
\(a\):
a coefficient in the polynomial or quadratic
\(h\):
height, step size, or half-life interval
\(k\):
constant, scale factor, index, or number of successes
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Write a quadratic by vertex and stretch.
132Factored form of a quadratic
\[y = a(x - r1)(x - r2)\]
\(r_1\):
root or solution of the quadratic
\(r_2\):
root or solution of the quadratic
\(a\):
a coefficient in the polynomial or quadratic
\(r\):
radius, rate, ratio, remainder, or root
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Write a quadratic by roots.
133Quadratic formula
\[x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}\]
\(a\):
a coefficient in the polynomial or quadratic
\(b\):
b coefficient in the polynomial or quadratic
\(x\):
unknown, input variable, or x-coordinate
Solve ax^2 + bx + c = 0.
134Discriminant formula
\[D=b^2-4ac\]
\(D\):
discriminant
\(b\):
b coefficient in the polynomial or quadratic
Determine the type and number of roots.
135Axis of symmetry formula
\[x=-\frac{b}{2a}\]
\(a\):
a coefficient in the polynomial or quadratic
\(b\):
b coefficient in the polynomial or quadratic
\(x\):
unknown, input variable, or x-coordinate
Find the vertical symmetry line.
136Vertex formula
\[h = -b/(2a), k = f(h)\]
\(a\):
a coefficient in the polynomial or quadratic
\(b\):
b coefficient in the polynomial or quadratic
\(f\):
function f, frequency, or matrix entry
\(h\):
height, step size, or half-life interval
\(k\):
constant, scale factor, index, or number of successes
Find the vertex from standard form.
137Completing the square formula
\[x^2+bx=\left(x+\frac{b}{2}\right)^2-\left(\frac{b}{2}\right)^2\]
\(b\):
b coefficient in the polynomial or quadratic
\(x\):
unknown, input variable, or x-coordinate
Rewrite a quadratic as a square plus constant.
138Sum of roots formula
\[r1 + r2 = -b/a\]
\(r_1\):
root or solution of the quadratic
\(r_2\):
root or solution of the quadratic
\(a\):
a coefficient in the polynomial or quadratic
\(b\):
b coefficient in the polynomial or quadratic
\(r\):
radius, rate, ratio, remainder, or root
Use Vieta relations for a quadratic.
139Product of roots formula
\[r1 r2 = c/a\]
\(r_1\):
root or solution of the quadratic
\(r_2\):
root or solution of the quadratic
\(a\):
a coefficient in the polynomial or quadratic
\(c\):
c coefficient in the polynomial or quadratic
\(r\):
radius, rate, ratio, remainder, or root
Use Vieta relations for a quadratic.
140Maximum value of a quadratic formula
\[\begin{gathered}\text{max = k when a < 0 in y = a(x - h)\^{}2 + k}\end{gathered}\]
\(a\):
a coefficient in the polynomial or quadratic
\(h\):
height, step size, or half-life interval
\(k\):
constant, scale factor, index, or number of successes
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Find peak value of a downward-opening parabola.
141Minimum value of a quadratic formula
\[\begin{gathered}\text{min = k when a > 0 in y = a(x - h)\^{}2 + k}\end{gathered}\]
\(a\):
a coefficient in the polynomial or quadratic
\(h\):
height, step size, or half-life interval
\(k\):
constant, scale factor, index, or number of successes
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Find lowest value of an upward-opening parabola.
142Parabola opening rule
\[\begin{gathered}\text{a > 0 opens up}\\\text{a < 0 opens down}\end{gathered}\]
\(a\):
a coefficient in the polynomial or quadratic
Read direction from the leading coefficient.
143Quadratic regression formula
\[y = ax^{2} + bx + c\]
\(c\):
c coefficient in the polynomial or quadratic
\(y\):
dependent variable, output, or y-coordinate
Fit a quadratic model to data.

10. Functions (16 formulae)

#Formula nameFormula or ruleVariables / notationUse
144Function notation formula
\[y = f(x)\]
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Name an output rule by its input.
145Domain rule
\[\begin{gathered}\text{domain = all allowed input values x}\end{gathered}\]
\(x\):
unknown, input variable, or x-coordinate
State the inputs for which a function is defined.
146Range rule
\[\begin{gathered}\text{range = \{f(x): x in domain\}}\end{gathered}\]
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
State all possible outputs.
147Composite function formula
\[(f\circ g)(x)=f(g(x))\]
\(f\):
function f, frequency, or matrix entry
\(g\):
function g, greatest common factor, or gravitational/constant term
\(x\):
unknown, input variable, or x-coordinate
Apply one function inside another.
148Inverse function formula
\[f^(-1)(f(x)) = x\]
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
Reverse a one-to-one function.
149Even function rule
\[\begin{gathered}\text{f(-x) = f(x)}\end{gathered}\]
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
Test y-axis symmetry.
150Odd function rule
\[\begin{gathered}\text{f(-x) = -f(x)}\end{gathered}\]
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
Test origin symmetry.
151Piecewise function formula
\[\begin{gathered}\text{f(x) = case rule by interval}\end{gathered}\]
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
Use different rules on different domains.
152Function transformation formulas
\[\begin{gathered}\text{y = a f(b(x - h)) + k}\end{gathered}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
\(h\):
height, step size, or half-life interval
\(k\):
constant, scale factor, index, or number of successes
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Combine shifts, reflections, stretches, and compressions.
153Horizontal shift formula
\[y = f(x - h)\]
\(f\):
function f, frequency, or matrix entry
\(h\):
height, step size, or half-life interval
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Move a graph right h units when h is positive.
154Vertical shift formula
\[y = f(x) + k\]
\(f\):
function f, frequency, or matrix entry
\(k\):
constant, scale factor, index, or number of successes
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Move a graph up k units when k is positive.
155Reflection formula
\[\begin{gathered}\text{y = -f(x) reflects over x-axis}\\\text{y = f(-x) reflects over y-axis}\end{gathered}\]
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Flip a graph across an axis.
156Stretch formula
\[\begin{gathered}\text{y = a f(x), |a| > 1}\end{gathered}\]
\(a\):
a known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Stretch outputs vertically.
157Compression formula
\[\begin{gathered}\text{y = a f(x), 0 < |a| < 1}\end{gathered}\]
\(a\):
a known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Compress outputs vertically.
158Average rate of change formula
\[\frac{f(b)-f(a)}{b-a}\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
Find average change over an interval.
159Difference quotient formula
\[\frac{f(x+h)-f(x)}{h}\]
\(f\):
function f, frequency, or matrix entry
\(h\):
height, step size, or half-life interval
\(x\):
unknown, input variable, or x-coordinate
Measure a function change over input step h.

11. Exponential & Logarithmic Functions (15 formulae)

#Formula nameFormula or ruleVariables / notationUse
160Exponential growth formula
\[y = a(1 + r)^{t}\]
\(a\):
a base, initial value, or constant
\(r\):
radius, rate, ratio, remainder, or root
\(t\):
time, parameter, or integration variable
\(y\):
dependent variable, output, or y-coordinate
Model growth by a fixed percent rate.
161Exponential decay formula
\[y = a(1 - r)^{t}\]
\(a\):
a base, initial value, or constant
\(r\):
radius, rate, ratio, remainder, or root
\(t\):
time, parameter, or integration variable
\(y\):
dependent variable, output, or y-coordinate
Model decay by a fixed percent rate.
162General exponential function formula
\[y = ab^{x}\]
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Model repeated multiplication by base b.
163Compound interest formula
\[A=P\left(1+\frac{r}{n}\right)^{nt}\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(P\):
principal amount
\(n\):
number of terms, sides, observations, trials, or periods
\(r\):
interest rate per period
Calculate interest compounded n times per year.
164Continuously compounded interest formula
\[A=Pe^{rt}\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
Calculate interest compounded continuously.
165Half-life formula
\[A = A0(1/2)^(t/h)\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(h\):
height, step size, or half-life interval
\(t\):
time, parameter, or integration variable
Model decay by repeated halving.
166Doubling time formula
\[T = \ln(2) / k for y = ae^(kt)\]
\(T\):
time, trapezoidal estimate, or transformation T
\(k\):
constant, scale factor, index, or number of successes
\(y\):
dependent variable, output, or y-coordinate
Find time needed to double under continuous growth.
167Logarithmic form formula
\[y = log_b(x)\]
\(b\):
b base, initial value, or constant
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Write the exponent needed to make x from base b.
168Exponential form formula
\[b^y=x\Longleftrightarrow y=\log_b(x)\]
\(b\):
b base, initial value, or constant
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Convert between log and exponential form.
169Product rule of logarithms
\[log_b(MN) = log_b(M) + log_b(N)\]
\(M\):
midpoint, matrix, mass, or midpoint sum
\(N\):
total count, population size, or original number
\(b\):
b base, initial value, or constant
Expand the log of a product.
170Quotient rule of logarithms
\[log_b(M/N) = log_b(M) - log_b(N)\]
\(M\):
midpoint, matrix, mass, or midpoint sum
\(N\):
total count, population size, or original number
\(b\):
b base, initial value, or constant
Expand the log of a quotient.
171Power rule of logarithms
\[log_b(M^{p}) = p log_b(M)\]
\(M\):
midpoint, matrix, mass, or midpoint sum
\(b\):
b base, initial value, or constant
\(p\):
rate, probability, or focus distance
Move an exponent out of a logarithm.
172Change of base formula
\[\log_b(x)=\frac{\ln x}{\ln b}\]
\(b\):
b base, initial value, or constant
\(x\):
unknown, input variable, or x-coordinate
Evaluate logs with a different base.
173Natural logarithm formula
\[\ln(x) = log_e(x)\]
\(e\):
Euler number for natural exponential growth, or a matrix entry
\(x\):
unknown, input variable, or x-coordinate
Use base e logarithms.
174Common logarithm formula
\[\log(x) = log_10(x)\]
\(x\):
unknown, input variable, or x-coordinate
Use base 10 logarithms.

12. Sequences & Series (11 formulae)

#Formula nameFormula or ruleVariables / notationUse
175Arithmetic sequence nth-term formula
\[a_n=a_1+(n-1)d\]
\(a_n\):
nth term of a sequence
\(a_1\):
first term of a sequence
\(a\):
a known number, coefficient, side length, or constant
\(d\):
common difference
\(n\):
number of terms, sides, observations, trials, or periods
Find a term in an arithmetic sequence.
176Arithmetic series sum formula
\[S_n=\frac{n}{2}\left(2a_1+(n-1)d\right)\]
\(a_1\):
first term of a sequence
\(S\):
sum, series total, sale price, or named set S
\(a\):
a known number, coefficient, side length, or constant
\(d\):
common difference
\(n\):
number of terms, sides, observations, trials, or periods
Sum the first n arithmetic terms.
177Geometric sequence nth-term formula
\[a_n=a_1r^{n-1}\]
\(a_n\):
nth term of a sequence
\(a_1\):
first term of a sequence
\(a\):
a known number, coefficient, side length, or constant
\(n\):
number of terms, sides, observations, trials, or periods
\(r\):
common ratio
Find a term in a geometric sequence.
178Geometric series sum formula
\[S_n=\frac{a_1(1-r^n)}{1-r},\quad r\ne1\]
\(a_1\):
first term of a sequence
\(S\):
sum, series total, sale price, or named set S
\(a\):
a known number, coefficient, side length, or constant
\(n\):
number of terms, sides, observations, trials, or periods
\(r\):
common ratio
Sum the first n geometric terms.
179Infinite geometric series formula
\[S=\frac{a_1}{1-r},\quad |r|<1\]
\(a_1\):
first term of a sequence
\(S\):
sum, series total, sale price, or named set S
\(a\):
a known number, coefficient, side length, or constant
\(r\):
common ratio
Sum an infinite geometric series that converges.
180Recursive sequence formula
\[\begin{gathered}\text{a\_n = f(a\_(n-1)), with starting value a\_1}\end{gathered}\]
\(a_n\):
nth term of a sequence
\(a_1\):
first term of a sequence
\(a\):
a known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
\(n\):
number of terms, sides, observations, trials, or periods
Define each term from earlier term(s).
181Fibonacci sequence formula
\[F_n = F_(n-1) + F_(n-2), F_1 = 1, F_2 = 1\]
\(F\):
function, force, or named coefficient F
\(n\):
number of terms, sides, observations, trials, or periods
Generate Fibonacci terms recursively.
182Sigma notation formula
\[\sum_{i=m}^{n} a_i\]
\(a_i\):
ith term or indexed value
\(a\):
a known number, coefficient, side length, or constant
\(i\):
index value or matrix row index
\(m\):
mass, slope, index, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Write repeated addition compactly.
183Partial sum formula
\[S_n = \sum_{i=1}^{n} a_i\]
\(a_i\):
ith term or indexed value
\(S\):
sum, series total, sale price, or named set S
\(a\):
a known number, coefficient, side length, or constant
\(i\):
index value or matrix row index
\(n\):
number of terms, sides, observations, trials, or periods
Add the first n terms of a sequence.
184Finite series formula
\[S_n = a_1 + a_2 + ... + a_n\]
\(a_n\):
nth term of a sequence
\(a_1\):
first term of a sequence
\(S\):
sum, series total, sale price, or named set S
\(a\):
a known number, coefficient, side length, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Represent a series with finitely many terms.
185Infinite series formula
\[S = \lim(n \to \infty) S_n\]
\(S\):
sum, series total, sale price, or named set S
\(n\):
number of terms, sides, observations, trials, or periods
Define an infinite series by a limit of partial sums.

13. Coordinate Geometry (15 formulae)

#Formula nameFormula or ruleVariables / notationUse
186Distance formula
\[d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\]
\(x_1\):
x-1 coordinate of a point
\(x_2\):
x-2 coordinate of a point
\(y_1\):
y-1 coordinate of a point
\(y_2\):
y-2 coordinate of a point
\(d\):
distance, diameter, divisor, or common difference
\(x\):
x-coordinate or input value
\(y\):
y-coordinate or output value
Find distance between two points.
187Midpoint formula
\[M=\left(\frac{x_1+x_2}{2},\frac{y_1+y_2}{2}\right)\]
\(x_1\):
x-1 coordinate of a point
\(x_2\):
x-2 coordinate of a point
\(y_1\):
y-1 coordinate of a point
\(y_2\):
y-2 coordinate of a point
\(M\):
midpoint, matrix, mass, or midpoint sum
\(x\):
x-coordinate or input value
\(y\):
y-coordinate or output value
Find the point halfway between two points.
188Section formula
\[P = ((mx2 + nx1)/(m+n), (my2 + ny1)/(m+n))\]
\(P\):
perimeter
\(m\):
mass, slope, index, or constant
\(n\):
number of terms, sides, observations, trials, or periods
Find a point dividing a segment in ratio m:n.
189Slope formula
\[m = (y2 - y1)/(x2 - x1)\]
\(x_1\):
x-1 coordinate of a point
\(x_2\):
x-2 coordinate of a point
\(y_1\):
y-1 coordinate of a point
\(y_2\):
y-2 coordinate of a point
\(m\):
slope
\(x\):
x-coordinate or input value
\(y\):
y-coordinate or output value
Find steepness between two points.
190Equation of a line
\[y - y1 = m(x - x1)\]
\(x_1\):
x-1 coordinate of a point
\(y_1\):
y-1 coordinate of a point
\(m\):
mass, slope, index, or constant
\(x\):
x-coordinate or input value
\(y\):
y-coordinate or output value
Write a line through a point with slope m.
191Equation of a circle
\[(x - h)^{2} + (y - k)^{2} = r^{2}\]
\(h\):
height, step size, or half-life interval
\(k\):
constant, scale factor, index, or number of successes
\(r\):
radius
\(x\):
x-coordinate or input value
\(y\):
y-coordinate or output value
Write a circle by center and radius.
192Center-radius form of a circle
\[(x - h)^{2} + (y - k)^{2} = r^{2}\]
\(h\):
height, step size, or half-life interval
\(k\):
constant, scale factor, index, or number of successes
\(r\):
radius
\(x\):
x-coordinate or input value
\(y\):
y-coordinate or output value
Read center (h,k) and radius r.
193General form of a circle
\[x^{2} + y^{2} + Dx + Ey + F = 0\]
\(F\):
function, force, or named coefficient F
\(x\):
x-coordinate or input value
\(y\):
y-coordinate or output value
Write a circle after expansion.
194Equation of a parabola
\[(x - h)^{2} = 4p(y - k) or (y - k)^{2} = 4p(x - h)\]
\(h\):
height, step size, or half-life interval
\(k\):
constant, scale factor, index, or number of successes
\(p\):
rate, probability, or focus distance
\(x\):
x-coordinate or input value
\(y\):
y-coordinate or output value
Represent a parabola by vertex and focus distance.
195Equation of an ellipse
\[(x - h)^{2}/a^{2} + (y - k)^{2}/b^{2} = 1\]
\(a\):
a side length or coordinate constant
\(b\):
b side length or coordinate constant
\(h\):
height, step size, or half-life interval
\(k\):
constant, scale factor, index, or number of successes
\(x\):
x-coordinate or input value
\(y\):
y-coordinate or output value
Represent an axis-aligned ellipse.
196Equation of a hyperbola
\[(x - h)^{2}/a^{2} - (y - k)^{2}/b^{2} = 1\]
\(a\):
a side length or coordinate constant
\(b\):
b side length or coordinate constant
\(h\):
height, step size, or half-life interval
\(k\):
constant, scale factor, index, or number of successes
\(x\):
x-coordinate or input value
\(y\):
y-coordinate or output value
Represent a horizontal axis-aligned hyperbola.
197Translation formula
\[(x, y) \to (x + a, y + b)\]
\(a\):
a side length or coordinate constant
\(b\):
b side length or coordinate constant
\(x\):
x-coordinate or input value
\(y\):
y-coordinate or output value
Move a point by vector (a,b).
198Reflection formula
\[\begin{gathered}\text{over x-axis: (x,y)->(x,-y)}\\\text{over y-axis: (x,y)->(-x,y)}\end{gathered}\]
\(x\):
x-coordinate or input value
\(y\):
y-coordinate or output value
Reflect a point across an axis.
199Rotation formula
\[\begin{gathered}\text{x' = x cos theta - y sin theta}\\\text{y' = x sin theta + y cos theta}\end{gathered}\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
\(x\):
x-coordinate or input value
\(y\):
y-coordinate or output value
Rotate a point about the origin.
200Dilation formula
\[(x, y) \to (kx, ky)\]
\(x\):
x-coordinate or input value
\(y\):
y-coordinate or output value
Scale a point from the origin by factor k.

14. Basic Geometry (16 formulae)

#Formula nameFormula or ruleVariables / notationUse
201Point formula
\[\begin{gathered}\text{point = (x, y)}\end{gathered}\]
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Represent a location with coordinates.
202Line formula
\[\begin{gathered}\text{Ax + By + C = 0}\end{gathered}\]
\(C\):
constant, coefficient, circumference, or third event as used in the row
Represent a straight line in general form.
203Ray formula
\[\begin{gathered}\text{R(t) = P + tv, t >= 0}\end{gathered}\]
\(P\):
perimeter
\(R\):
radius, right sum, range endpoint, or outer radius
\(t\):
time, parameter, or integration variable
Represent a ray from endpoint P in direction v.
204Line segment formula
\[length = \sqrt{(x2 - x1)^{2} + (y2 - y1)^{2}}\]
\(x_1\):
x-1 coordinate of a point
\(x_2\):
x-2 coordinate of a point
\(y_1\):
y-1 coordinate of a point
\(y_2\):
y-2 coordinate of a point
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Find the length of a segment.
205Angle sum formula
\[\begin{gathered}\text{angles on a line = 180ยฐ}\\\text{angles around a point = 360ยฐ}\end{gathered}\]
\(a\):
a side length or coordinate constant
Use standard angle totals.
206Complementary angles formula
\[A + B = 90ยฐ\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(B\):
angle, base area, or set B as used in the row
Relate two angles that make a right angle.
207Supplementary angles formula
\[A + B = 180ยฐ\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(B\):
angle, base area, or set B as used in the row
Relate two angles that make a straight angle.
208Vertical angles rule
\[\begin{gathered}\text{vertical angles are equal}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Use opposite angles formed by intersecting lines.
209Linear pair rule
\[\begin{gathered}\text{adjacent linear-pair angles sum to 180ยฐ}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Use angles sharing a straight line.
210Triangle angle sum formula
\[A+B+C=180^\circ\]
\(A\):
area or angle A, depending on the row
\(B\):
angle, base area, or set B as used in the row
\(C\):
angle C
Find missing angles in triangles.
211Exterior angle theorem
\[\begin{gathered}\text{exterior angle = sum of two remote interior angles}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Relate a triangle exterior angle to interior angles.
212Polygon interior angle sum formula
\[\text{sum}=(n-2)180^\circ\]
\(n\):
number of terms, sides, observations, trials, or periods
Find total interior angle measure.
213Polygon exterior angle sum formula
\[\sum = 360ยฐ\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Find total exterior angle measure for a convex polygon.
214Regular polygon interior angle formula
\[\text{each interior angle}=\frac{(n-2)180^\circ}{n}\]
\(n\):
number of terms, sides, observations, trials, or periods
Find one angle in a regular polygon.
215Regular polygon exterior angle formula
\[each exterior angle = 360ยฐ/n\]
\(n\):
number of terms, sides, observations, trials, or periods
Find one exterior angle in a regular polygon.
216Diagonal formula for polygons
\[\text{diagonals}=\frac{n(n-3)}{2}\]
\(n\):
number of terms, sides, observations, trials, or periods
Count diagonals in an n-sided polygon.

15. Triangles (16 formulae)

#Formula nameFormula or ruleVariables / notationUse
217Triangle perimeter formula
\[P = a + b + c\]
\(P\):
perimeter
\(a\):
a side length or coordinate constant
\(b\):
b side length or coordinate constant
\(c\):
c side length or coordinate constant
Add all three side lengths.
218Triangle area formula
\[A=\frac{1}{2}bh\]
\(A\):
area or angle A, depending on the row
Find area from base and height.
219Right triangle area formula
\[A = (1/2)(leg1)(leg2)\]
\(A\):
area or angle A, depending on the row
Use perpendicular legs as base and height.
220Equilateral triangle area formula
\[A=\frac{\sqrt{3}}{4}s^2\]
\(A\):
area or angle A, depending on the row
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
Find area from side length s.
221Heron's formula
\[A=\sqrt{s(s-a)(s-b)(s-c)},\quad s=\frac{a+b+c}{2}\]
\(A\):
area or angle A, depending on the row
\(a\):
a side length or coordinate constant
\(b\):
b side length or coordinate constant
\(c\):
c side length or coordinate constant
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
Find triangle area from three sides.
222Pythagorean theorem
\[a^2+b^2=c^2\]
\(a\):
a side length or coordinate constant
\(b\):
b side length or coordinate constant
\(c\):
c side length or coordinate constant
Relate legs and hypotenuse in a right triangle.
223Converse of Pythagorean theorem
\[\begin{gathered}\text{if a\^{}2 + b\^{}2 = c\^{}2, triangle is right}\end{gathered}\]
\(a\):
a side length or coordinate constant
\(b\):
b side length or coordinate constant
\(c\):
c side length or coordinate constant
Test whether side lengths form a right triangle.
224Special right triangle 45-45-90 formulas
\[x,\ x,\ x\sqrt{2}\]
\(x\):
unknown, input variable, or x-coordinate
Use side ratios for an isosceles right triangle.
225Special right triangle 30-60-90 formulas
\[x,\ x\sqrt{3},\ 2x\]
\(x\):
unknown, input variable, or x-coordinate
Use side ratios opposite 30ยฐ, 60ยฐ, and 90ยฐ.
226Triangle inequality theorem
\[a + b > c, a + c > b, b + c > a\]
\(a\):
a side length or coordinate constant
\(b\):
b side length or coordinate constant
\(c\):
c side length or coordinate constant
Check whether three sides can form a triangle.
227Similar triangles proportion formula
\[\begin{gathered}\text{a/b = c/d = scale factor}\end{gathered}\]
\(a\):
a side length or coordinate constant
\(b\):
b side length or coordinate constant
\(c\):
c side length or coordinate constant
\(d\):
distance, diameter, divisor, or common difference
Relate corresponding sides in similar triangles.
228Congruent triangles rules
\[\begin{gathered}\text{SSS, SAS, ASA, AAS, HL}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Prove triangles have matching size and shape.
229Median formula
\[m_a = (1/2)\sqrt{2b^{2} + 2c^{2} - a^{2}}\]
\(a\):
a side length or coordinate constant
\(b\):
b side length or coordinate constant
\(c\):
c side length or coordinate constant
\(m\):
mass, slope, index, or constant
Find the median to side a.
230Altitude formula
\[h = 2A / b\]
\(A\):
area or angle A, depending on the row
\(b\):
b side length or coordinate constant
\(h\):
height, step size, or half-life interval
Find height from area and base.
231Angle bisector theorem
\[BD/DC = AB/AC\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Relate side split by an angle bisector.
232Perpendicular bisector theorem
\[\begin{gathered}\text{if P is on perpendicular bisector of AB, PA = PB}\end{gathered}\]
\(P\):
perimeter
Use equal distances from segment endpoints.

16. Quadrilaterals (16 formulae)

#Formula nameFormula or ruleVariables / notationUse
233Square perimeter formula
\[P = 4s\]
\(P\):
perimeter
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
Find square perimeter from side length.
234Square area formula
\[A = s^{2}\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
Find square area from side length.
235Rectangle perimeter formula
\[P=2(l+w)\]
\(P\):
perimeter
\(l\):
length or slant height
\(w\):
width, weight, or vector component
Find rectangle perimeter.
236Rectangle area formula
\[A=lw\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
Find rectangle area.
237Parallelogram perimeter formula
\[P = 2(a + b)\]
\(P\):
perimeter
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
Find perimeter from adjacent side lengths.
238Parallelogram area formula
\[A = bh\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
Find area from base and height.
239Rhombus perimeter formula
\[P = 4s\]
\(P\):
perimeter
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
Find rhombus perimeter.
240Rhombus area formula
\[A=\frac{d_1d_2}{2}\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(d\):
distance, diameter, divisor, or common difference
Find rhombus area from diagonals.
241Trapezoid area formula
\[A=\frac{1}{2}(b_1+b_2)h\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(b\):
b known number, coefficient, side length, or constant
\(h\):
height, step size, or half-life interval
Find trapezoid area from bases and height.
242Kite area formula
\[A = (d1 d2)/2\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(d\):
distance, diameter, divisor, or common difference
Find kite area from diagonals.
243Diagonal formula of rectangle
\[d = \sqrt{l^{2} + w^{2}}\]
\(d\):
distance, diameter, divisor, or common difference
\(l\):
length or slant height
\(w\):
width, weight, or vector component
Find a rectangle diagonal.
244Diagonal formula of square
\[d = s \sqrt{2}\]
\(d\):
distance, diameter, divisor, or common difference
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
Find a square diagonal.
245Properties of parallelograms formulas
\[\begin{gathered}\text{opposite sides equal}\\\text{opposite angles equal}\\\text{diagonals bisect}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Use core parallelogram relationships.
246Properties of rectangles formulas
\[\begin{gathered}\text{all angles = 90ยฐ}\\\text{d\^{}2 = l\^{}2 + w\^{}2}\end{gathered}\]
\(d\):
distance, diameter, divisor, or common difference
\(l\):
length or slant height
\(w\):
width, weight, or vector component
Use rectangle angle and diagonal facts.
247Properties of rhombuses formulas
\[\begin{gathered}\text{all sides equal}\\\text{diagonals are perpendicular}\\\text{A = d1d2/2}\end{gathered}\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(d\):
distance, diameter, divisor, or common difference
Use rhombus side and diagonal facts.
248Properties of squares formulas
\[\begin{gathered}\text{P = 4s}\\\text{A = s\^{}2}\\\text{d = s sqrt(2)}\end{gathered}\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(P\):
perimeter
\(d\):
distance, diameter, divisor, or common difference
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
Use square side, area, and diagonal facts.

17. Circles (14 formulae)

#Formula nameFormula or ruleVariables / notationUse
249Circle circumference formula
\[C=2\pi r=\pi d\]
\(\pi\):
the constant pi, approximately 3.14159
\(C\):
circumference
\(d\):
diameter
\(r\):
radius
Find distance around a circle.
250Circle area formula
\[A=\pi r^2\]
\(\pi\):
the constant pi, approximately 3.14159
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(r\):
radius
Find area inside a circle.
251Radius formula
\[r = d/2 = C/(2pi)\]
\(\pi\):
the constant pi, approximately 3.14159
\(C\):
circumference
\(d\):
diameter
\(r\):
radius
Find radius from diameter or circumference.
252Diameter formula
\[d = 2r = C/\pi\]
\(\pi\):
the constant pi, approximately 3.14159
\(C\):
circumference
\(d\):
diameter
\(r\):
radius
Find diameter from radius or circumference.
253Arc length formula
\[s=r\theta\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
\(r\):
radius
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
Find arc length when theta is in radians.
254Sector area formula
\[A=\frac{1}{2}r^2\theta\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(r\):
radius
Find sector area when theta is in radians.
255Segment area formula
\[A = (r^{2}/2)(\theta - \sin \theta)\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(r\):
radius
Find area between chord and arc.
256Central angle formula
\[\theta = s/r\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
\(r\):
radius
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
Find central angle from arc length and radius.
257Inscribed angle formula
\[inscribed angle = (1/2)(intercepted arc)\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Relate an inscribed angle to its arc.
258Chord length formula
\[chord = 2r \sin(\theta/2)\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
\(r\):
radius
Find chord length from radius and central angle.
259Tangent length formula
\[PA = PB\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Use equal tangent lengths from the same external point.
260Secant-tangent theorem
\[\text{tangent}^2=(\text{external secant})(\text{whole secant})\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Solve tangent and secant lengths.
261Intersecting chords theorem
\[a\times b=c\times d\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
diameter
Use products of chord segments inside a circle.
262Circle equation formula
\[(x - h)^{2} + (y - k)^{2} = r^{2}\]
\(h\):
height, step size, or half-life interval
\(k\):
constant, scale factor, index, or number of successes
\(r\):
radius
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Graph a circle in the coordinate plane.

18. Three-Dimensional Geometry (19 formulae)

#Formula nameFormula or ruleVariables / notationUse
263Cube volume formula
\[V = s^{3}\]
\(V\):
volume, value, or vector V
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
Find volume from cube side length.
264Cube surface area formula
\[SA = 6s^{2}\]
\(SA\):
surface area
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
Find total area of six square faces.
265Rectangular prism volume formula
\[V = lwh\]
\(V\):
volume, value, or vector V
Find box volume.
266Rectangular prism surface area formula
\[SA = 2(lw + lh + wh)\]
\(SA\):
surface area
Find total area of a rectangular prism.
267Triangular prism volume formula
\[V=(\text{area of triangular base})\times\text{length}\]
\(V\):
volume, value, or vector V
Find volume of a triangular prism.
268Prism surface area formula
\[SA = 2B + Ph\]
\(SA\):
surface area
\(B\):
angle, base area, or set B as used in the row
Find surface area from base area B and base perimeter P.
269Cylinder volume formula
\[V=\pi r^2h\]
\(\pi\):
the constant pi, approximately 3.14159
\(V\):
volume, value, or vector V
\(h\):
height, step size, or half-life interval
\(r\):
radius
Find cylinder volume.
270Cylinder surface area formula
\[SA = 2pi r^{2} + 2pi rh\]
\(SA\):
surface area
\(\pi\):
the constant pi, approximately 3.14159
\(r\):
radius
Find total cylinder surface area.
271Cone volume formula
\[V = (1/3)\pi r^{2} h\]
\(\pi\):
the constant pi, approximately 3.14159
\(V\):
volume, value, or vector V
\(h\):
height, step size, or half-life interval
\(r\):
radius
Find cone volume.
272Cone surface area formula
\[SA = \pi r^{2} + \pi r l\]
\(SA\):
surface area
\(\pi\):
the constant pi, approximately 3.14159
\(l\):
length or slant height
\(r\):
radius
Find total cone surface area with slant height l.
273Sphere volume formula
\[V=\frac{4}{3}\pi r^3\]
\(\pi\):
the constant pi, approximately 3.14159
\(V\):
volume, value, or vector V
\(r\):
radius
Find sphere volume.
274Sphere surface area formula
\[SA = 4pi r^{2}\]
\(SA\):
surface area
\(\pi\):
the constant pi, approximately 3.14159
\(r\):
radius
Find sphere surface area.
275Hemisphere volume formula
\[V = (2/3)\pi r^{3}\]
\(\pi\):
the constant pi, approximately 3.14159
\(V\):
volume, value, or vector V
\(r\):
radius
Find half-sphere volume.
276Hemisphere surface area formula
\[\begin{gathered}\text{SA = 3pi r\^{}2 total}\\\text{curved area = 2pi r\^{}2}\end{gathered}\]
\(SA\):
surface area
\(\pi\):
the constant pi, approximately 3.14159
\(r\):
radius
Find total or curved hemisphere surface area.
277Pyramid volume formula
\[V = (1/3)Bh\]
\(V\):
volume, value, or vector V
Find pyramid volume from base area and height.
278Pyramid surface area formula
\[SA = B + (1/2)Pl\]
\(SA\):
surface area
\(B\):
angle, base area, or set B as used in the row
Find pyramid surface area with slant height l.
279Frustum volume formula
\[V = (h/3)(A1 + A2 + \sqrt{A1A2})\]
\(A_1\):
area of one of the parallel bases
\(A_2\):
area of one of the parallel bases
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(V\):
volume, value, or vector V
\(h\):
height, step size, or half-life interval
Find volume between two similar parallel bases.
280Composite solid volume formula
\[V_total = \sum V_parts - \sum V_removed\]
\(V\):
volume, value, or vector V
Combine volumes of multiple solids.
281Density formula
\[\rho = m / V\]
\(\rho\):
density
\(V\):
volume, value, or vector V
\(m\):
mass, slope, index, or constant
Relate mass and volume.

19. Measurement (12 formulae)

#Formula nameFormula or ruleVariables / notationUse
282Length conversion formulas
\[\begin{gathered}\text{new length = old length x conversion factor}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Convert between length units.
283Area conversion formulas
\[\begin{gathered}\text{new area = old area x (linear factor)\^{}2}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Convert between area units.
284Volume conversion formulas
\[\begin{gathered}\text{new volume = old volume x (linear factor)\^{}3}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Convert between volume units.
285Mass conversion formulas
\[\begin{gathered}\text{new mass = old mass x conversion factor}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Convert between mass units.
286Time conversion formulas
\[\begin{gathered}\text{new time = old time x conversion factor}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Convert seconds, minutes, hours, days, and years.
287Temperature conversion formulas
\[F = (9/5)C + 32; C = (5/9)(F - 32); K = C + 273.15\]
\(C\):
constant, coefficient, circumference, or third event as used in the row
\(F\):
function, force, or named coefficient F
Convert Celsius, Fahrenheit, and Kelvin.
288Speed formula
\[speed = distance / time\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Measure how fast distance is covered.
289Distance formula
\[\begin{gathered}\text{distance = rate x time}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Find distance from rate and time.
290Time formula
\[\begin{gathered}\text{time = distance / rate}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Find time from distance and rate.
291Rate formula
\[\begin{gathered}\text{rate = quantity / time}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Find change per unit time.
292Unit conversion formula
\[\begin{gathered}\text{converted value = original value x unit ratio}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Convert units using a factor equal to 1.
293Dimensional analysis formula
\[\begin{gathered}\text{value x (desired unit / given unit)}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Cancel units to check a conversion path.

20. Trigonometry (20 formulae)

#Formula nameFormula or ruleVariables / notationUse
294Sine ratio formula
\[\sin\theta=\frac{\text{opposite}}{\text{hypotenuse}}\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
Find sine in a right triangle.
295Cosine ratio formula
\[\cos\theta=\frac{\text{adjacent}}{\text{hypotenuse}}\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
Find cosine in a right triangle.
296Tangent ratio formula
\[\tan\theta=\frac{\text{opposite}}{\text{adjacent}}\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
Find tangent in a right triangle.
297Reciprocal trigonometric ratios
\[\begin{gathered}\text{csc theta = 1/sin theta}\\\text{sec theta = 1/cos theta}\\\text{cot theta = 1/tan theta}\end{gathered}\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
Use reciprocal trig functions.
298Pythagorean trigonometric identity
\[\sin^2\theta+\cos^2\theta=1\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
Simplify trig expressions.
299Complementary angle identities
\[\begin{gathered}\text{sin(90ยฐ - theta) = cos theta}\\\text{tan(90ยฐ - theta) = cot theta}\end{gathered}\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
Relate cofunctions of complementary angles.
300Unit circle formulas
\[(x, y) = (\cos \theta, \sin \theta)\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Read sine and cosine from a unit-circle point.
301Radian measure formula
\[\theta = s/r\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
\(r\):
radius, rate, ratio, remainder, or root
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
Define radians from arc length and radius.
302Degree-radian conversion formula
\[\text{radians}=\text{degrees}\times\frac{\pi}{180}\]
\(\pi\):
the constant pi, approximately 3.14159
Convert angle units.
303Arc length using radians formula
\[s = r \theta\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
\(r\):
radius, rate, ratio, remainder, or root
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
Find arc length with theta in radians.
304Sector area using radians formula
\[A = (1/2)r^{2} \theta\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
\(A\):
area or angle A, depending on the row
\(r\):
radius, rate, ratio, remainder, or root
Find sector area with theta in radians.
305Law of sines
\[\frac{a}{\sin A}=\frac{b}{\sin B}=\frac{c}{\sin C}\]
\(A\):
area or angle A, depending on the row
\(B\):
angle, base area, or set B as used in the row
\(C\):
angle C
\(a\):
a side length or coordinate constant
\(b\):
b side length or coordinate constant
\(c\):
c side length or coordinate constant
Solve non-right triangles with side-angle pairs.
306Law of cosines
\[c^2=a^2+b^2-2ab\cos C\]
\(C\):
angle C
\(a\):
a side length or coordinate constant
\(b\):
b side length or coordinate constant
\(c\):
c side length or coordinate constant
Solve non-right triangles with included angle or three sides.
307Area of triangle using sine formula
\[A = (1/2)ab \sin C\]
\(A\):
area or angle A, depending on the row
\(C\):
angle C
Find triangle area from two sides and included angle.
308Sum identities
\[\sin(a+b)=\sin a \cos b + \cos a \sin b; \cos(a+b)=\cos a \cos b - \sin a \sin b\]
\(a\):
a side length or coordinate constant
\(b\):
b side length or coordinate constant
Expand trig functions of sums.
309Difference identities
\[\sin(a-b)=\sin a \cos b - \cos a \sin b; \cos(a-b)=\cos a \cos b + \sin a \sin b\]
\(a\):
a side length or coordinate constant
\(b\):
b side length or coordinate constant
Expand trig functions of differences.
310Double-angle identities
\[\sin 2x = 2sin x \cos x; \cos 2x = \cos^{2} x - \sin^{2} x\]
\(x\):
unknown, input variable, or x-coordinate
Simplify trig expressions with twice an angle.
311Half-angle identities
\[\sin^{2}(x/2) = (1 - \cos x)/2; \cos^{2}(x/2) = (1 + \cos x)/2\]
\(x\):
unknown, input variable, or x-coordinate
Work with half-angle expressions.
312Inverse trigonometric formulas
\[\theta = \sin^(-1)(x), \cos^(-1)(x), or \tan^(-1)(x)\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
\(x\):
unknown, input variable, or x-coordinate
Find an angle from a trig ratio.
313Trigonometric equation formulas
\[\sin x = a \to x = \arcsin(a) + 2pi k or \pi - \arcsin(a) + 2pi k\]
\(\pi\):
the constant pi, approximately 3.14159
\(a\):
a side length or coordinate constant
\(k\):
constant, scale factor, index, or number of successes
Write general solutions for trig equations.

21. Data, Statistics & Probability (33 formulae)

#Formula nameFormula or ruleVariables / notationUse
314Mean formula
\[\bar{x}=\frac{\sum x_i}{n}\]
\(x_i\):
ith data value or sample value
\(i\):
index value or matrix row index
\(n\):
number of terms, sides, observations, trials, or periods
\(x\):
unknown, input variable, or x-coordinate
Find the arithmetic average.
315Median formula
\[\begin{gathered}\text{median = middle ordered value}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Find the center of ordered data.
316Mode formula
\[\begin{gathered}\text{mode = most frequent value}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Find the most repeated value.
317Range formula
\[range = maximum - minimum\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Measure spread from smallest to largest.
318Interquartile range formula
\[\operatorname{IQR}=Q_3-Q_1\]
\(IQR\):
interquartile range
\(Q\):
quartile, matrix quotient, or named quantity Q
Measure spread of the middle half.
319Quartile formula
\[Q_k position = k(n + 1)/4\]
\(Q\):
quartile, matrix quotient, or named quantity Q
\(k\):
constant, scale factor, index, or number of successes
\(n\):
number of terms, sides, observations, trials, or periods
Estimate quartile positions in ordered data.
320Percentile formula
\[\text{percentile rank}=\frac{\text{values below}}{n}\times100\]
\(n\):
number of terms, sides, observations, trials, or periods
Measure relative standing in data.
321Mean absolute deviation formula
\[MAD = (\sum |x_i - mean|) / n\]
\(MAD\):
mean absolute deviation
\(x_i\):
ith data value or sample value
\(i\):
index value or matrix row index
\(n\):
number of terms, sides, observations, trials, or periods
\(x\):
unknown, input variable, or x-coordinate
Measure average absolute distance from the mean.
322Variance formula
\[\begin{gathered}\text{variance = mean of squared deviations}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Measure average squared spread.
323Standard deviation formula
\[\begin{gathered}\text{standard deviation = sqrt(variance)}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Measure typical distance from the mean.
324Population variance formula
\[\sigma^2=\frac{\sum(x_i-\mu)^2}{N}\]
\(x_i\):
ith data value or sample value
\(\mu\):
population mean
\(\sigma\):
population standard deviation
\(N\):
total count, population size, or original number
\(i\):
index value or matrix row index
\(x\):
unknown, input variable, or x-coordinate
Find variance for a full population.
325Sample variance formula
\[s^2=\frac{\sum(x_i-\bar{x})^2}{n-1}\]
\(x_i\):
ith data value or sample value
\(i\):
index value or matrix row index
\(n\):
number of terms, sides, observations, trials, or periods
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
\(x\):
unknown, input variable, or x-coordinate
Estimate variance from a sample.
326Population standard deviation formula
\[\sigma = \sqrt{(\sum (x_i - \mu)^{2}) / N}\]
\(x_i\):
ith data value or sample value
\(\mu\):
population mean
\(\sigma\):
population standard deviation
\(N\):
total count, population size, or original number
\(i\):
index value or matrix row index
\(x\):
unknown, input variable, or x-coordinate
Find population standard deviation.
327Sample standard deviation formula
\[s = \sqrt{(\sum (x_i - xbar)^{2}) / (n - 1)}\]
\(x_i\):
ith data value or sample value
\(i\):
index value or matrix row index
\(n\):
number of terms, sides, observations, trials, or periods
\(s\):
semiperimeter, arc length, side length, or sample standard deviation
\(x\):
unknown, input variable, or x-coordinate
Find sample standard deviation.
328z-score formula
\[z=\frac{x-\mu}{\sigma}\]
\(\mu\):
population mean
\(\sigma\):
population standard deviation
\(x\):
unknown, input variable, or x-coordinate
\(z\):
z-score, z-coordinate, or standard normal value
Measure standard deviations from the mean.
329Weighted mean formula
\[\bar{x}_w=\frac{\sum w_ix_i}{\sum w_i}\]
\(x_i\):
ith data value or sample value
\(w_i\):
weight assigned to the ith value
\(i\):
index value or matrix row index
\(w\):
width, weight, or vector component
\(x\):
unknown, input variable, or x-coordinate
Average values with weights.
330Frequency table formula
\[\begin{gathered}\text{N = sum f\_i}\end{gathered}\]
\(f_i\):
frequency for the ith value or class
\(N\):
total count, population size, or original number
\(f\):
function f, frequency, or matrix entry
\(i\):
index value or matrix row index
Summarize counts by category or value.
331Relative frequency formula
\[relative frequency = f / N\]
\(N\):
total count, population size, or original number
\(f\):
function f, frequency, or matrix entry
Convert a count to a share.
332Probability formula
\[P(E)=\frac{\text{favorable outcomes}}{\text{total outcomes}}\]
\(E\):
event
\(P\):
probability
Find basic probability.
333Experimental probability formula
\[P(E) = successes / trials\]
\(E\):
event
\(P\):
probability
Estimate probability from results.
334Theoretical probability formula
\[\begin{gathered}\text{P(E) = favorable equally likely outcomes / all equally likely outcomes}\end{gathered}\]
\(E\):
event
\(P\):
probability
Find probability from a model.
335Complement probability formula
\[P(not E) = 1 - P(E)\]
\(E\):
event
\(P\):
probability
Find the probability an event does not occur.
336Addition rule of probability
\[P(A \cup B) = P(A) + P(B) - P(A \cap B)\]
\(A\):
event or set A
\(B\):
event or set B
\(P\):
probability
Find probability of A or B.
337Multiplication rule of probability
\[P(A \cap B) = P(A)P(B|A)\]
\(A\):
event or set A
\(B\):
event or set B
\(P\):
probability
Find probability of A and B.
338Conditional probability formula
\[P(A\mid B)=\frac{P(A\cap B)}{P(B)}\]
\(A\):
event or set A
\(B\):
event or set B
\(P\):
probability
Find probability of A given B.
339Independent events formula
\[P(A \cap B) = P(A)P(B)\]
\(A\):
event or set A
\(B\):
event or set B
\(P\):
probability
Test or use independence.
340Dependent events formula
\[\begin{gathered}\text{P(A then B) = P(A)P(B|A)}\end{gathered}\]
\(A\):
event or set A
\(B\):
event or set B
\(P\):
probability
Handle probability when the first event changes the second.
341Mutually exclusive events formula
\[P(A \cap B) = 0\]
\(A\):
event or set A
\(B\):
event or set B
\(P\):
probability
Use when events cannot happen together.
342Permutation formula
\[{}_nP_r=\frac{n!}{(n-r)!}\]
\(n\):
number of terms, sides, observations, trials, or periods
\(r\):
radius, rate, ratio, remainder, or root
Count ordered selections.
343Combination formula
\[{}_nC_r=\frac{n!}{r!(n-r)!}\]
\(n\):
number of terms, sides, observations, trials, or periods
\(r\):
radius, rate, ratio, remainder, or root
Count unordered selections.
344Binomial probability formula
\[P(X=k)=\binom{n}{k}p^k(1-p)^{n-k}\]
\(P\):
probability
\(X\):
random variable, x-axis quantity, or set X
\(k\):
constant, scale factor, index, or number of successes
\(n\):
number of terms, sides, observations, trials, or periods
\(p\):
probability of success
Find exactly k successes in n independent trials.
345Expected value formula
\[E(X)=\sum xP(x)\]
\(E\):
event
\(P\):
probability
\(X\):
random variable, x-axis quantity, or set X
\(x\):
unknown, input variable, or x-coordinate
Find long-run average outcome.
346Normal distribution formula
\[f(x)=1/(\sigma \sqrt{2pi}) e^(-((x-\mu)^{2})/(2sigma^{2}))\]
\(\mu\):
population mean
\(\sigma\):
population standard deviation
\(\pi\):
the constant pi, approximately 3.14159
\(e\):
Euler number for natural exponential growth, or a matrix entry
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
Use the normal probability density curve.

22. Financial Mathematics (18 formulae)

#Formula nameFormula or ruleVariables / notationUse
347Simple interest formula
\[I=Prt\]
\(I\):
interest amount
Calculate interest without compounding.
348Compound interest formula
\[A=P\left(1+\frac{r}{n}\right)^{nt}\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(P\):
principal amount
\(n\):
number of terms, sides, observations, trials, or periods
\(r\):
interest rate per period
Calculate interest with periodic compounding.
349Continuous compound interest formula
\[A=Pe^{rt}\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
Calculate continuously compounded growth.
350Future value formula
\[FV=PV(1+r)^n\]
\(PV\):
present value
\(FV\):
future value
\(n\):
number of terms, sides, observations, trials, or periods
\(r\):
interest rate per period
Find future value after n periods.
351Present value formula
\[PV=\frac{FV}{(1+r)^n}\]
\(PV\):
present value
\(FV\):
future value
\(n\):
number of terms, sides, observations, trials, or periods
\(r\):
interest rate per period
Discount a future value to today.
352Loan payment formula
\[PMT=\frac{Pr(1+r)^n}{(1+r)^n-1}\]
\(PMT\):
fixed periodic payment
\(P\):
principal amount
\(n\):
number of terms, sides, observations, trials, or periods
\(r\):
interest rate per period
Find fixed payment for an amortizing loan.
353Mortgage payment formula
\[M=\frac{Pr(1+r)^n}{(1+r)^n-1}\]
\(M\):
mortgage payment
\(P\):
principal amount
\(n\):
number of terms, sides, observations, trials, or periods
\(r\):
interest rate per period
Find a fixed mortgage principal-and-interest payment.
354Amortization formula
\[balance = P(1+r)^{k} - PMT((1+r)^{k} - 1)/r\]
\(PMT\):
fixed periodic payment
\(P\):
principal amount
\(k\):
constant, scale factor, index, or number of successes
\(r\):
interest rate per period
Estimate remaining loan balance after k payments.
355Depreciation formula
\[\begin{gathered}\text{straight-line depreciation = (cost - salvage) / useful life}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Spread asset cost evenly over time.
356Markup formula
\[\text{markup}=\text{selling price}-\text{cost},\quad \text{markup \%}=\frac{\text{markup}}{\text{cost}}\times100\%\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Measure price increase over cost.
357Markdown formula
\[\text{markdown}=\text{original price}-\text{sale price},\quad \text{markdown \%}=\frac{\text{markdown}}{\text{original}}\times100\%\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Measure price reduction from original price.
358Discount formula
\[\begin{gathered}\text{sale price = original price(1 - discount rate)}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Apply a percentage discount.
359Sales tax formula
\[\begin{gathered}\text{total = price(1 + tax rate)}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Add sales tax to a purchase.
360Profit formula
\[\begin{gathered}\text{profit = revenue - cost}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Measure gain after costs.
361Loss formula
\[\begin{gathered}\text{loss = cost - revenue}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Measure shortfall when cost exceeds revenue.
362Commission formula
\[\text{commission}=\text{sales}\times\text{commission rate}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Calculate earnings from sales rate.
363Break-even formula
\[\begin{gathered}\text{break-even units = fixed costs / (price - variable cost)}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Find units needed to cover costs.
364Inflation formula
\[\begin{gathered}\text{real value = nominal value / (1 + inflation rate)\^{}n}\end{gathered}\]
\(n\):
number of terms, sides, observations, trials, or periods
Adjust money for price-level change.

23. Calculus Readiness / Precalculus (16 formulae)

#Formula nameFormula or ruleVariables / notationUse
365Limit notation formula
\[\lim(x \to a) f(x) = L\]
\(L\):
length, left sum, or lower endpoint as used in the row
\(a\):
a known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
State the value approached by a function.
366Average rate of change formula
\[(f(b) - f(a)) / (b - a)\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
Find slope of a secant line.
367Instantaneous rate of change formula
\[f'(a) = \lim(h \to 0) (f(a+h) - f(a))/h\]
\(a\):
a known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
\(h\):
small input change or subinterval width
Define derivative at a point.
368Difference quotient formula
\[(f(x+h) - f(x)) / h\]
\(f\):
function f, frequency, or matrix entry
\(h\):
small input change or subinterval width
\(x\):
unknown, input variable, or x-coordinate
Prepare for derivative calculations.
369Secant line slope formula
\[m_secant = (f(b) - f(a)) / (b - a)\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
\(m\):
slope
Find slope through two points on a curve.
370Tangent line slope formula
\[m_tangent = f'(a)\]
\(a\):
a known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
\(m\):
slope
Find slope of a curve at one point.
371End behavior formulas
\[study f(x) as x \to \infty and x \to -\infty\]
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
Describe graph behavior far left and right.
372Polynomial end behavior rule
\[\begin{gathered}\text{leading term a\_n x\^{}n controls end behavior}\end{gathered}\]
\(a_n\):
nth term of a sequence
\(a\):
a coefficient in the polynomial or quadratic
\(n\):
number of terms, sides, observations, trials, or periods
\(x\):
unknown, input variable, or x-coordinate
Predict polynomial tails.
373Rational function asymptote formulas
\[\begin{gathered}\text{vertical: denominator = 0}\\\text{horizontal/slant: compare degrees}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Analyze rational-function boundaries.
374Horizontal asymptote formula
\[\begin{gathered}\text{deg top < deg bottom -> y=0}\\\text{equal degrees -> y=leading coefficient ratio}\end{gathered}\]
\(y\):
dependent variable, output, or y-coordinate
Find horizontal asymptotes.
375Vertical asymptote formula
\[\begin{gathered}\text{set simplified denominator = 0}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Find x-values where a rational function is unbounded.
376Slant asymptote formula
\[\begin{gathered}\text{slant asymptote = polynomial quotient when deg top = deg bottom + 1}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Find oblique asymptotes by division.
377Rational function simplification formula
\[\begin{gathered}\text{factor numerator and denominator, then cancel common nonzero factors}\end{gathered}\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Simplify rational expressions and identify holes.
378Trigonometric graph formulas
\[y = A \sin(B(x - C)) + D; period = 2pi/|B|\]
\(\pi\):
the constant pi, approximately 3.14159
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(B\):
second quantity, event, matrix, or coefficient named B
\(C\):
constant of integration
\(D\):
difference, determinant, diameter, or named constant D
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Graph sine and cosine transformations.
379Exponential graph formulas
\[y = ab^(x - h) + k\]
\(h\):
small input change or subinterval width
\(k\):
constant, scale factor, index, or number of successes
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Graph exponential transformations.
380Logarithmic graph formulas
\[y = a log_b(x - h) + k\]
\(a\):
a base, initial value, or constant
\(b\):
b base, initial value, or constant
\(h\):
small input change or subinterval width
\(k\):
constant, scale factor, index, or number of successes
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Graph logarithmic transformations.

24. Matrices & Vectors (18 formulae)

#Formula nameFormula or ruleVariables / notationUse
381Matrix addition formula
\[(A+B)_{ij}=A_{ij}+B_{ij}\]
\(A\):
matrix or first event, depending on the row
\(B\):
second quantity, event, matrix, or coefficient named B
Add matching entries of same-size matrices.
382Matrix subtraction formula
\[(A - B)_ij = A_ij - B_ij\]
\(A\):
matrix or first event, depending on the row
\(B\):
second quantity, event, matrix, or coefficient named B
Subtract matching entries of same-size matrices.
383Scalar multiplication formula
\[(cA)_ij = cA_ij\]
Notation:
This row is a rule or named structure; use the named quantities and conditions exactly as stated.
Multiply every matrix entry by a scalar.
384Matrix multiplication formula
\[(AB)_{ij}=\sum_k A_{ik}B_{kj}\]
\(A\):
matrix or first event, depending on the row
\(B\):
second quantity, event, matrix, or coefficient named B
\(k\):
constant, scale factor, index, or number of successes
Multiply rows by columns.
385Identity matrix formula
\[AI = IA = A\]
\(A\):
matrix or first event, depending on the row
Use the matrix version of 1.
386Zero matrix formula
\[A + 0 = A\]
\(A\):
matrix or first event, depending on the row
Use the matrix version of 0.
387Determinant of 2x2 matrix
\[\det\begin{bmatrix}a&b\\c&d\end{bmatrix}=ad-bc\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
Find determinant of a 2 by 2 matrix.
388Determinant of 3x3 matrix
\[a(ei - fh) - b(di - fg) + c(dh - eg)\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
Find determinant of [[a,b,c],[d,e,f],[g,h,i]].
389Inverse of 2x2 matrix
\[A^{-1}=\frac{1}{ad-bc}\begin{bmatrix}d&-b\\-c&a\end{bmatrix}\]
\(A\):
matrix or first event, depending on the row
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
Invert a 2 by 2 matrix when determinant is nonzero.
390Matrix equation formula
\[Ax = b\]
\(b\):
b known number, coefficient, side length, or constant
Represent linear equations compactly.
391Vector magnitude formula
\[||v|| = \sqrt{v1^{2} + v2^{2} + ... + vn^{2}}\]
\(v\):
vector v, velocity, or value
Find vector length.
392Vector addition formula
\[<a,b> + <c,d> = <a+c,b+d>\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
Add vectors component by component.
393Vector subtraction formula
\[<a,b> - <c,d> = <a-c,b-d>\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(c\):
c known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
Subtract vectors component by component.
394Scalar multiplication of vector formula
\[k<a,b> = <ka,kb>\]
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(k\):
constant, scale factor, index, or number of successes
Scale a vector.
395Dot product formula
\[u \cdot v = \sum u_i v_i = ||u||||v||\cos \theta\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
\(i\):
index value or matrix row index
\(u\):
substitution variable or vector u
\(v\):
vector v, velocity, or value
Measure projection and angle relation.
396Cross product formula
\[u\times v=\langle u_2v_3-u_3v_2,\ u_3v_1-u_1v_3,\ u_1v_2-u_2v_1\rangle\]
\(u\):
substitution variable or vector u
\(v\):
vector v, velocity, or value
Find a 3D vector perpendicular to two vectors.
397Unit vector formula
\[u_hat = u / ||u||\]
\(u\):
substitution variable or vector u
Convert a nonzero vector to length 1.
398Direction angle formula
\[\theta = atan2(y, x)\]
\(\theta\):
angle measure, usually in radians unless degrees are stated
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Find vector direction from components.

25. Logic, Sets & Discrete Math (15 formulae)

#Formula nameFormula or ruleVariables / notationUse
399Set union formula
\[A\cup B=\{x:x\in A\ \text{or}\ x\in B\}\]
\(A\):
event or set A
\(B\):
event or set B
\(x\):
unknown, input variable, or x-coordinate
Combine elements from either set.
400Set intersection formula
\[A\cap B=\{x:x\in A\ \text{and}\ x\in B\}\]
\(A\):
event or set A
\(B\):
event or set B
\(x\):
unknown, input variable, or x-coordinate
Find shared elements.
401Set complement formula
\[A'=\{x\in U:x\notin A\}\]
\(A\):
event or set A
\(x\):
unknown, input variable, or x-coordinate
Find elements outside a set within universe U.
402Difference of sets formula
\[A-B=\{x:x\in A\ \text{and}\ x\notin B\}\]
\(A\):
event or set A
\(B\):
event or set B
\(x\):
unknown, input variable, or x-coordinate
Remove B elements from A.
403Cartesian product formula
\[A\times B=\{(a,b):a\in A,\ b\in B\}\]
\(A\):
event or set A
\(B\):
event or set B
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
Build ordered pairs from two sets.
404Venn diagram formula
\[n(A \cup B) = n(A) + n(B) - n(A \cap B)\]
\(A\):
event or set A
\(B\):
event or set B
\(n\):
number of terms, sides, observations, trials, or periods
Count elements in overlapping sets.
405Inclusion-exclusion principle
\[n(A \cup B \cup C) = n(A)+n(B)+n(C)-n(AB)-n(AC)-n(BC)+n(ABC)\]
\(A\):
event or set A
\(B\):
event or set B
\(C\):
constant, coefficient, circumference, or third event as used in the row
\(n\):
number of terms, sides, observations, trials, or periods
Count overlapping groups without double-counting.
406Truth table formulas
\[\begin{gathered}\text{not p, p and q, p or q, p -> q}\end{gathered}\]
\(p\):
rate, probability, or focus distance
\(q\):
quotient, probability of failure, or integer part
Evaluate compound logical statements.
407Conditional statement formula
\[p \to q is equivalent to not p or q\]
\(p\):
rate, probability, or focus distance
\(q\):
quotient, probability of failure, or integer part
Represent "if p, then q."
408Converse formula
\[q \to p\]
\(p\):
rate, probability, or focus distance
\(q\):
quotient, probability of failure, or integer part
Reverse a conditional statement.
409Inverse formula
\[not p \to not q\]
\(p\):
rate, probability, or focus distance
\(q\):
quotient, probability of failure, or integer part
Negate both parts of a conditional.
410Contrapositive formula
\[not q \to not p\]
\(p\):
rate, probability, or focus distance
\(q\):
quotient, probability of failure, or integer part
Use a logically equivalent form of p -> q.
411Direct proof structure
\[\begin{gathered}\text{assume p, use definitions/theorems, conclude q}\end{gathered}\]
\(p\):
rate, probability, or focus distance
\(q\):
quotient, probability of failure, or integer part
Rule:
Read the text condition before applying the symbols or calculator workflow.
Prove a conditional directly.
412Indirect proof structure
\[\begin{gathered}\text{assume not q, derive contradiction, conclude q}\end{gathered}\]
\(q\):
quotient, probability of failure, or integer part
Rule:
Read the text condition before applying the symbols or calculator workflow.
Prove by contradiction or contrapositive reasoning.
413Mathematical induction formula
\[\begin{gathered}\text{base case true}\\\text{if P(k) -> P(k+1), then P(n) true for n >= base}\end{gathered}\]
\(P\):
principal, perimeter, probability, or point P as used in the row
\(k\):
constant, scale factor, index, or number of successes
\(n\):
number of terms, sides, observations, trials, or periods
Rule:
Read the text condition before applying the symbols or calculator workflow.
Prove statements over integers.

26. Advanced K-12 / AP & IB Extension (27 formulae)

#Formula nameFormula or ruleVariables / notationUse
414Derivative definition formula
\[f'(x)=\lim_{h\to0}\frac{f(x+h)-f(x)}{h}\]
\(f\):
function f, frequency, or matrix entry
\(h\):
height, step size, or half-life interval
\(x\):
unknown, input variable, or x-coordinate
Define instantaneous rate of change.
415Power rule
\[\frac{d}{dx}x^n=nx^{n-1}\]
\(d\):
distance, diameter, divisor, or common difference
\(n\):
number of terms, sides, observations, trials, or periods
\(x\):
unknown, input variable, or x-coordinate
Differentiate powers of x.
416Product rule
\[(fg)'=f'g+fg'\]
\(f\):
function f, frequency, or matrix entry
\(g\):
function g, greatest common factor, or gravitational/constant term
Differentiate a product.
417Quotient rule
\[\left(\frac{f}{g}\right)'=\frac{f'g-fg'}{g^2}\]
\(f\):
function f, frequency, or matrix entry
\(g\):
function g, greatest common factor, or gravitational/constant term
Differentiate a quotient.
418Chain rule
\[\frac{d}{dx}f(g(x))=f'(g(x))g'(x)\]
\(d\):
distance, diameter, divisor, or common difference
\(f\):
function f, frequency, or matrix entry
\(g\):
function g, greatest common factor, or gravitational/constant term
\(x\):
unknown, input variable, or x-coordinate
Differentiate a composition.
419Derivatives of trigonometric functions
\[d(\sin x)=\cos x; d(\cos x)=-\sin x; d(\tan x)=\sec^{2} x\]
\(d\):
distance, diameter, divisor, or common difference
\(x\):
unknown, input variable, or x-coordinate
Differentiate basic trig functions.
420Derivatives of exponential functions
\[d(e^{x})=e^{x}; d(a^{x})=a^{x} \ln a\]
\(a\):
a base, initial value, or constant
\(d\):
distance, diameter, divisor, or common difference
\(e\):
Euler number for natural exponential growth, or a matrix entry
\(x\):
unknown, input variable, or x-coordinate
Differentiate exponential functions.
421Derivatives of logarithmic functions
\[d(\ln x)=1/x; d(log_a x)=1/(x \ln a)\]
\(a\):
a base, initial value, or constant
\(d\):
distance, diameter, divisor, or common difference
\(x\):
unknown, input variable, or x-coordinate
Differentiate logarithmic functions.
422Implicit differentiation formula
\[dy/dx = -F_x/F_y for F(x,y)=0\]
\(F_x\):
partial derivative with respect to the indicated variable
\(F_y\):
partial derivative with respect to the indicated variable
\(F\):
function, force, or named coefficient F
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Differentiate equations not solved for y.
423Related rates formula
\[\begin{gathered}\text{differentiate the relation with respect to t}\end{gathered}\]
\(t\):
time, parameter, or integration variable
Connect changing quantities over time.
424Optimization formula
\[\begin{gathered}\text{critical points solve f'(x)=0 or f'(x) undefined}\end{gathered}\]
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
Find maxima and minima under constraints.
425Riemann sum formula
\[\sum f(x_i^*)\Delta x\]
\(x_i\):
ith data value or sample value
\(x_i\times \):
sample point inside the ith subinterval
\(\Delta x\):
width of each subinterval or change in x
\(f\):
function f, frequency, or matrix entry
\(i\):
index value or matrix row index
\(x\):
unknown, input variable, or x-coordinate
Approximate area by rectangles.
426Left Riemann sum formula
\[L_n = \sum from i=0 to n-1 f(a + i \Delta x)\Delta x\]
\(\Delta x\):
width of each subinterval or change in x
\(L\):
length, left sum, or lower endpoint as used in the row
\(a\):
a known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
\(i\):
index value or matrix row index
\(n\):
number of terms, sides, observations, trials, or periods
\(x\):
unknown, input variable, or x-coordinate
Approximate area using left endpoints.
427Right Riemann sum formula
\[R_n = \sum from i=1 to n f(a + i \Delta x)\Delta x\]
\(\Delta x\):
width of each subinterval or change in x
\(R\):
radius, right sum, range endpoint, or outer radius
\(a\):
a known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
\(i\):
index value or matrix row index
\(n\):
number of terms, sides, observations, trials, or periods
\(x\):
unknown, input variable, or x-coordinate
Approximate area using right endpoints.
428Midpoint Riemann sum formula
\[M_n = \sum from i=1 to n f((x_(i-1)+x_i)/2)\Delta x\]
\(x_i\):
ith data value or sample value
\(\Delta x\):
width of each subinterval or change in x
\(M\):
midpoint, matrix, mass, or midpoint sum
\(f\):
function f, frequency, or matrix entry
\(i\):
index value or matrix row index
\(n\):
number of terms, sides, observations, trials, or periods
\(x\):
unknown, input variable, or x-coordinate
Approximate area using midpoints.
429Trapezoidal rule
\[T_n = (\Delta x/2)(f(x0) + 2f(x1) + ... + 2f(x_(n-1)) + f(xn))\]
\(x_1\):
x-1 coordinate of a point
\(\Delta x\):
width of each subinterval or change in x
\(T\):
time, trapezoidal estimate, or transformation T
\(f\):
function f, frequency, or matrix entry
\(n\):
number of terms, sides, observations, trials, or periods
\(x\):
unknown, input variable, or x-coordinate
Approximate area with trapezoids.
430Definite integral formula
\[\int_a^b f(x)\,dx=F(b)-F(a)\]
\(F\):
function, force, or named coefficient F
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
Compute signed area using an antiderivative.
431Indefinite integral formula
\[\int f(x) dx = F(x) + C\]
\(C\):
constant of integration
\(F\):
function, force, or named coefficient F
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
Find a family of antiderivatives.
432Fundamental theorem of calculus
\[\frac{d}{dx}\int_a^x f(t)\,dt=f(x),\quad \int_a^b f(x)\,dx=F(b)-F(a)\]
\(F\):
antiderivative or function F
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(d\):
distance, diameter, divisor, or common difference
\(f\):
function f, frequency, or matrix entry
\(t\):
time, parameter, or integration variable
\(x\):
unknown, input variable, or x-coordinate
Connect differentiation and integration.
433Basic integration rules
\[\int x^n\,dx=\frac{x^{n+1}}{n+1}+C,\quad n\ne-1\]
\(C\):
constant of integration
\(n\):
number of terms, sides, observations, trials, or periods
\(x\):
unknown, input variable, or x-coordinate
Integrate basic powers.
434Integration by substitution
\[u = g(x), du = g'(x)dx\]
\(g\):
function g, greatest common factor, or gravitational/constant term
\(u\):
substitution variable or vector u
\(x\):
unknown, input variable, or x-coordinate
Reverse the chain rule.
435Area under a curve formula
\[A = \int_{a}^{b} f(x) dx, f(x) \ge 0\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(f\):
function f, frequency, or matrix entry
\(x\):
unknown, input variable, or x-coordinate
Find area between a curve and the x-axis.
436Area between curves formula
\[A = \int_{a}^{b} (top - bottom) dx\]
\(A\):
area, amount, angle, event, or matrix named A as used in the row
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
Find area between two curves.
437Volume by disk method
\[V = \pi \int_{a}^{b} R(x)^{2} dx\]
\(\pi\):
the constant pi, approximately 3.14159
\(R\):
radius, right sum, range endpoint, or outer radius
\(V\):
volume, value, or vector V
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(x\):
unknown, input variable, or x-coordinate
Find volume of revolution with no hole.
438Volume by washer method
\[V = \pi \int_{a}^{b} (R(x)^{2} - r(x)^{2}) dx\]
\(\pi\):
the constant pi, approximately 3.14159
\(R\):
radius, right sum, range endpoint, or outer radius
\(V\):
volume, value, or vector V
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
\(r\):
radius, rate, ratio, remainder, or root
\(x\):
unknown, input variable, or x-coordinate
Find volume of revolution with a hole.
439Volume by shell method
\[V=2\pi\int_a^b \text{radius}\times\text{height}\,dx\]
\(\pi\):
the constant pi, approximately 3.14159
\(V\):
volume, value, or vector V
\(a\):
a known number, coefficient, side length, or constant
\(b\):
b known number, coefficient, side length, or constant
Find volume of revolution using cylindrical shells.
440Differential equation separation formula
\[\frac{dy}{dx}=g(x)h(y)\Longrightarrow \int\frac{dy}{h(y)}=\int g(x)\,dx+C\]
\(C\):
constant of integration
\(g\):
function g, greatest common factor, or gravitational/constant term
\(h\):
height, step size, or half-life interval
\(x\):
unknown, input variable, or x-coordinate
\(y\):
dependent variable, output, or y-coordinate
Solve separable first-order differential equations.

Frequently Asked Questions

This page includes 440 numbered formula entries across 26 K-12 and advanced high-school math topics, from number sense through AP and IB calculus readiness.

No. The early sections cover elementary and middle-school arithmetic, fractions, measurement, geometry, and probability. The later sections cover algebra, trigonometry, matrices, vectors, logic, and calculus readiness.

No. Use the page as a reference first. Prioritize formulas your class or exam requires, then practice substitution, units, graph meaning, and when the formula is valid.

Some math items are best stated as rules or structures, such as order of operations, congruent triangle rules, proof structures, and divisibility tests. They are included because students still use them like formula references.

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Sources & References

  1. 1.OpenStax - Algebra and Trigonometry 2e Index(Accessed May 2026)
  2. 2.OpenStax - Precalculus 2e Basic Functions and Identities(Accessed May 2026)
  3. 3.OpenStax - Calculus Volume 1, Fundamental Theorem of Calculus(Accessed May 2026)
  4. 4.Khan Academy - Perimeter & area(Accessed May 2026)