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Mathematics

Formula references and worked examples for the algebra, geometry, trigonometry, and calculus topics that show up most often in coursework and exams.

Algebra Geometry Trigonometry Calculus How to study math Common mistakes

Foundations

Algebra formula sheet

ConceptFormula
Quadratic formulax = (-b ± √(b² - 4ac)) / 2a, for ax² + bx + c = 0
Slope of a linem = (y² - y¹) / (x² - x¹)
Slope-intercept formy = mx + b
Point-slope formy - y¹ = m(x - x¹)
Difference of squaresa² - b² = (a + b)(a - b)
Perfect square trinomial(a ± b)² = a² ± 2ab + b²
Exponent rulesam·an = am+n, (am)n = amn, a0 = 1
Logarithm identitylogb(x) = y means by = x

Worked example: solve 2x² + 3x - 2 = 0. Here a=2, b=3, c=-2. Plug into the quadratic formula: x = (-3 ± √(9 + 16)) / 4 = (-3 ± 5) / 4, giving x = 0.5 or x = -2.

Shapes & Space

Geometry formula sheet

ShapeAreaPerimeter / Circumference
RectangleA = lwP = 2(l + w)
TriangleA = ½bhP = a + b + c
CircleA = πr²C = 2πr
TrapezoidA = ½(b¹ + b²)h-
SolidVolumeSurface Area
Rectangular prismV = lwhSA = 2(lw + lh + wh)
CylinderV = πr²hSA = 2πrh + 2πr²
SphereV = &frac43;πr³SA = 4πr²
ConeV = ⅓πr²h-

Pythagorean theorem: for a right triangle with legs a, b and hypotenuse c, a² + b² = c².

Angles

Trigonometry reference

RatioDefinition (right triangle)
Sinesin(θ) = opposite / hypotenuse
Cosinecos(θ) = adjacent / hypotenuse
Tangenttan(θ) = opposite / adjacent
Pythagorean identitysin²(θ) + cos²(θ) = 1
Law of sinesa/sin(A) = b/sin(B) = c/sin(C)
Law of cosinesc² = a² + b² - 2ab·cos(C)

Memory trick: SOH-CAH-TOA - Sine = Opposite/Hypotenuse, Cosine = Adjacent/Hypotenuse, Tangent = Opposite/Adjacent.

Change & Accumulation

Calculus quick reference

RuleFormula
Power rule (derivative)d/dx[xn] = nxn-1
Product ruled/dx[fg] = f'g + fg'
Quotient ruled/dx[f/g] = (f'g - fg') / g²
Chain ruled/dx[f(g(x))] = f'(g(x))·g'(x)
Power rule (integral)∫xndx = xn+1/(n+1) + C
Derivative of sin/cosd/dx[sin x] = cos x, d/dx[cos x] = -sin x

Strategy

How to study math effectively

Do problems, don't just read them
Watching a worked example feels like understanding, but math is a skill - you only build it by solving problems yourself, including ones you get wrong.
Redo your mistakes from scratch
When you miss a problem, don't just read the correct answer. Close the solution and try the problem again a day later.
Build a formula sheet as you go
Use the Flashcard Builder to turn each new formula into a card the moment you learn it, rather than cramming them all before a test.

Common Mistakes

Where students lose marks in math

Patterns we see again and again in student work. Each one is fixable once you know to look for it.

Sign errors when distributing a negative
-(x - 3) becomes -x - 3 instead of -x + 3. This single error accounts for a surprising share of wrong answers on algebra tests. Slow down at every minus sign in front of parentheses and distribute it to every term inside.
Cancelling terms instead of factors
You can cancel a common factor from the top and bottom of a fraction, not a common term. (x + 2)/2 is not x + 1. Before cancelling anything, ask whether it multiplies the whole numerator and the whole denominator.
Using the formula without checking what it needs
The quadratic formula requires the equation to be in the form ax² + bx + c = 0. Students plug coefficients from 2x² + 3x = 2 without moving the 2 across first. Any time you reach for a formula, check the form it expects.
Degrees and radians
Calculators default to one or the other. A trig answer that is wildly wrong is very often a mode problem. Check the mode before the test, and get used to which unit each course expects.
Forgetting the constant of integration
Every indefinite integral ends in + C. It is a small thing that graders check every time, and it matters when you are solving for a specific solution using an initial condition.

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