SAT Math Formula Sheet

SAT Math Formula Sheet (Detailed)

Jump links at the top, clean print layout, and “what it’s for” notes so students don’t just memorize symbols.



Print tip: choose “Save as PDF” to make a one-click downloadable sheet.
How to use this: When you miss a question, tag it to a section below and re-do it using the formulas listed there.
The goal is not “memorize everything,” it’s “know what tool matches what situation.”

1) Algebra Basics (core tools)

A. Exponent Laws

a^m · a^n = a^(m+n)
a^m / a^n = a^(m−n) (a ≠ 0)
(a^m)^n = a^(mn)
(ab)^n = a^n b^n
(a/b)^n = a^n / b^n (b ≠ 0)
a^0 = 1 (a ≠ 0)
a^(−n) = 1/a^n

Roots as exponents

ⁿ√a = a^(1/n)
a^(m/n) = ⁿ√(a^m)

B. Radicals & Simplifying

√(ab) = √a · √b (a,b ≥ 0)
√(a/b) = √a / √b (b > 0)
√(k^2) = |k|
√(x^2) = |x| (important!)
Common trap: √(x²) is not “x” automatically. It’s |x|. SAT sometimes tests this.

C. Factoring Patterns

GCF: ax + ay = a(x + y)
Difference of squares: a² − b² = (a − b)(a + b)
Perfect square trinomials:
a² + 2ab + b² = (a + b)²
a² − 2ab + b² = (a − b)²
Trinomial: x² + (p+q)x + pq = (x+p)(x+q)

Grouping (4 terms)

ax + ay + bx + by = a(x+y) + b(x+y) = (a+b)(x+y)

D. Fractions & Rational Expressions

a/b + c/d = (ad + bc)/bd
a/b − c/d = (ad − bc)/bd
(a/b)·(c/d) = ac/bd
(a/b)÷(c/d) = (a/b)·(d/c)
Domain rule: If an expression has a denominator, that denominator cannot be 0.
Even if something cancels later, the original restriction still matters.

2) Lines & Systems

A. Slope + Line Forms

Slope between points: m = (y₂ − y₁)/(x₂ − x₁)
Slope-intercept: y = mx + b
Point-slope: y − y₁ = m(x − x₁)
Standard: Ax + By = C

Intercepts

x-intercept: set y = 0, solve for x
y-intercept: set x = 0, solve for y
Fast recognition: In y=mx+b, the slope is the coefficient of x. b is the y-intercept.

B. Parallel & Perpendicular

Parallel lines: same slope
Perpendicular (non-vertical): m₁m₂ = −1
Negative reciprocal: if m = a/b, perp slope = −b/a

Vertical / Horizontal

Vertical line: x = constant (slope undefined)
Horizontal line: y = constant (slope 0)

C. Systems (2 equations)

One solution: lines intersect once
No solution: parallel distinct lines
Infinite solutions: same line (equivalent equations)

Quick check for “same line”

If you can multiply one equation by a constant to get the other, they’re the same line.

D. Inequalities

If you multiply/divide by a negative, flip the inequality sign.
Example: −2x > 6 → x < −3

Compound inequalities

−a < x < a means x is between −a and a
x < −a OR x > a means outside that range

3) Functions & Graph Features

A. Function notation

f(x) means “output when input is x”
If f(x)=2x+3, then f(5)=2(5)+3=13

Domain & Range (SAT level)

Domain: allowed x-values (inputs)
Range: possible y-values (outputs)
Restrictions often come from: denominator=0, even root of negative

B. Average rate of change

Average rate of change on [a,b]: (f(b) − f(a)) / (b − a)
Think of this as the slope of the secant line between (a,f(a)) and (b,f(b)).

C. Transformations

f(x) + k : shift up k
f(x) − k : shift down k
f(x − h) : shift right h
f(x + h) : shift left h
a·f(x) : vertical stretch by |a| (flip if a<0)
f(ax) : horizontal shrink by factor 1/|a| (flip if a<0)
Common confusion: inside changes go “opposite.”
f(x−3) shifts RIGHT 3, not left.

D. Composition (sometimes)

(f ∘ g)(x) = f(g(x))

Inverse idea (when asked)

Swap x and y, solve for y, then rename y as f⁻¹(x).
Check: f(f⁻¹(x)) = x

4) Quadratics & Polynomials

A. Quadratic forms

Standard: y = ax² + bx + c
Vertex: y = a(x − h)² + k (vertex = (h,k))
Factored: y = a(x − r₁)(x − r₂) (roots r₁, r₂)

Axis + vertex x-value

Axis of symmetry: x = −b/(2a)

B. Quadratic formula + discriminant

x = (−b ± √(b² − 4ac)) / (2a)
Δ = b² − 4ac
Discriminant meaning:
Δ > 0 → 2 real roots
Δ = 0 → 1 real root (double root)
Δ < 0 → no real roots

C. Completing the square (fast version)

x² + bx = (x + b/2)² − (b/2)²

Example: x² + 6x = (x+3)² − 9

D. Polynomial extras

Remainder theorem: remainder when f(x) ÷ (x − a) is f(a)
Factor theorem: if f(a)=0, then (x − a) is a factor
End behavior (rough): leading term controls big-x behavior

5) Exponential & Rational Models

A. Exponential basics

y = a·b^x (b>1 growth, 0<b<1 decay)

Percent growth/decay model

y = a(1 + r)^t (growth)
y = a(1 − r)^t (decay)

B. Exponential interpretation

a = initial value (when x=0)
b = growth factor per 1 unit of x
If something grows 8% each period, b = 1.08.
If it decays 12% each period, b = 0.88.

C. Rational functions (SAT level)

f(x) = (polynomial)/(polynomial)
Domain excludes values that make denominator 0

Asymptotes (common cases)

Vertical asymptote: denominator = 0 (that doesn’t cancel)
Horizontal asymptote (degree rule):
deg(top) < deg(bottom) → y=0
deg(top) = deg(bottom) → y = (leading coeffs ratio)

D. Simplifying rational expressions

Factor numerator and denominator, cancel common factors.
But keep original domain restrictions.

6) Percent, Ratio, Units

A. Percent basics

percent = (part/whole) × 100%
part = (percent as decimal) × whole
whole = part / (percent as decimal)

Percent change

Percent change = (new − old)/old × 100%

B. Multipliers (fastest way)

Increase by r% → multiply by (1 + r/100)
Decrease by r% → multiply by (1 − r/100)
Two changes compound. Example: +20% then −20% is not back to original.
It’s ×1.2×0.8 = ×0.96 (a 4% net decrease).

C. Ratios & proportions

a:b = a/b
a/b = c/d → ad = bc

Direct variation

y = kx (k is constant of proportionality)

D. Units & rates

rate = distance/time
distance = rate·time
Work problems: combined rate = sum of individual rates

7) Data, Statistics, Probability

A. Center & spread

Mean = (sum of values)/(number of values)
Median = middle value (sorted) or avg of 2 middle values
Range = max − min

Boxplot pieces (concept)

Min, Q1, Median, Q3, Max
IQR = Q3 − Q1

B. Standard deviation (what SAT expects)

Bigger SD → more spread out
Add constant to all values → SD unchanged
Multiply all values by k → SD multiplied by |k|
SAT usually tests SD conceptually, not with the full calculation.

C. Scatterplots & lines of best fit

Positive association: as x increases, y tends to increase
Negative association: as x increases, y tends to decrease
Stronger association: points closer to a line

Residual

Residual = actual y − predicted y

D. Probability rules

P(A) = favorable/total
P(not A) = 1 − P(A)
P(A or B) = P(A) + P(B) − P(A and B)
Independent: P(A and B) = P(A)P(B)
Conditional: P(A|B) = P(A and B)/P(B)

Two-way tables

Joint: cell/total
Conditional: cell/(row total or column total)

E. Counting (when it shows up)

n! = n·(n−1)·…·2·1
Permutations: nP r = n!/(n−r)!
Combinations: nC r = n!/[r!(n−r)!]

8) Geometry & Coordinate Geometry

A. Triangles

Angle sum: A + B + C = 180°
Area: A = (1/2)bh
Pythagorean theorem: a² + b² = c²
45-45-90: legs x, hyp x√2
30-60-90: short x, long x√3, hyp 2x

Similar triangles

Scale factor = k
Perimeter scales by k
Area scales by k²

B. Circles

Circumference: C = 2πr
Area: A = πr²
Arc length: (θ/360)·2πr
Sector area: (θ/360)·πr²

Circle equations

Center (0,0): x² + y² = r²
Center (h,k): (x − h)² + (y − k)² = r²

C. Polygons & area formulas

Rectangle: A=lw, P=2l+2w
Parallelogram: A=bh
Trapezoid: A=(1/2)(b₁+b₂)h
Interior angle sum: (n−2)·180°

D. Coordinate geometry

Distance: d = √[(x₂ − x₁)² + (y₂ − y₁)²]
Midpoint: ((x₁+x₂)/2, (y₁+y₂)/2)

Slope reminder

m = (y₂ − y₁)/(x₂ − x₁)

E. 3D solids (common)

Rectangular prism: V=lwh, SA=2(lw+lh+wh)
Cylinder: V=πr²h, SA=2πr²+2πrh
Cone (sometimes): V=(1/3)πr²h
Sphere (sometimes): V=(4/3)πr³, SA=4πr²
SAT sometimes includes cone/sphere. If you want, I can add a “SAT-provided vs must-memorize” label.

9) Trigonometry (SAT level)

A. SOH-CAH-TOA

sin(θ) = opposite / hypotenuse
cos(θ) = adjacent / hypotenuse
tan(θ) = opposite / adjacent

One identity you might see

sin²(θ) + cos²(θ) = 1

B. Degrees ↔ Radians

π radians = 180°
degrees → radians: × (π/180)
radians → degrees: × (180/π)

Arc length (radians version)

s = rθ (θ in radians)

C. Special values

sin 30°=1/2, cos 30°=√3/2, tan 30°=1/√3
sin 45°=√2/2, cos 45°=√2/2, tan 45°=1
sin 60°=√3/2, cos 60°=1/2, tan 60°=√3
Special triangles are the fastest way to remember these, not memorizing a table.

10) Quick Checklist (high-frequency formulas)

If you only want the “core SAT page,” this is it. Everything else above is the expanded version with notes.
  • Slope: (y₂−y₁)/(x₂−x₁)
  • Line forms: y=mx+b, y−y₁=m(x−x₁)
  • Distance: √[(x₂−x₁)²+(y₂−y₁)²] • Midpoint: ((x₁+x₂)/2,(y₁+y₂)/2)
  • Quadratic vertex x: −b/(2a) • Quadratic formula: (−b±√(b²−4ac))/(2a)
  • Discriminant: b²−4ac
  • Pythagorean: a²+b²=c² • Triangle area: (1/2)bh
  • Circle: C=2πr, A=πr²
  • Percent change: (new−old)/old
  • Growth/decay: a(1±r)^t
  • Probability: P(A or B)=P(A)+P(B)−P(A and B), P(A|B)=P(A and B)/P(B)
  • Trig: sin=opp/hyp, cos=adj/hyp, tan=opp/adj