IGCSE Maths Formula Sheet

The IGCSE Maths syllabus is broad and challenging, requiring students to master a wide array of mathematical techniques. To help you navigate this demanding course, we have created a comprehensive IGCSE Maths formula sheet. This carefully organised resource includes all the crucial formulas you need to know, covering algebra, geometry, trigonometry, probability, mensuration, and logarithms. The international nature of the IGCSE means the standards are high, and having these formulas memorised is a significant advantage. Whether you are studying the core or extended curriculum, this guide will serve as a reliable reference point throughout your studies. Use it to check your work, guide your revision, and ensure you are fully prepared to tackle any question the exam paper throws your way with complete confidence.

algebra

Quadratic Formula

Class 10algebra

x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

Roots of a quadratic equation ax^2 + bx + c = 0

#roots#equations#quadratic

Difference of Squares

Class 10algebra

a^2 - b^2 = (a - b)(a + b)

Factoring difference of two squares

#factoring#polynomials

Sum of Cubes

Class 10algebra

a^3 + b^3 = (a + b)(a^2 - ab + b^2)

Factoring sum of two cubes

#factoring#cubes

Difference of Cubes

Class 10algebra

a^3 - b^3 = (a - b)(a^2 + ab + b^2)

Factoring difference of two cubes

#factoring#cubes

Binomial Theorem

Class 12algebra

(x+y)^n = \sum_{k=0}^{n} \binom{n}{k} x^{n-k} y^k

Expansion of a binomial power

#expansion#series#binomial

Arithmetic Progression (nth Term)

Class 10algebra

a_n = a_1 + (n-1)d

nth term of an AP with common difference d

#sequences#ap

Arithmetic Progression (Sum)

Class 10algebra

S_n = \frac{n}{2}(2a_1 + (n-1)d) = \frac{n}{2}(a_1 + a_n)

Sum of first n terms of an AP

#series#ap

Geometric Progression (nth Term)

Class 12algebra

a_n = a_1 r^{n-1}

nth term of a GP with common ratio r

#sequences#gp

Geometric Progression (Sum)

Class 12algebra

S_n = \frac{a_1(1-r^n)}{1-r} \quad (r \neq 1)

Sum of first n terms of a GP

#series#gp

Infinite Geometric Series

Class 12algebra

S_\infty = \frac{a_1}{1-r} \quad (|r| < 1)

Sum of infinite GP when ratio is strictly between -1 and 1

#series#infinite

Vieta's Formulas (Quadratic)

Class 10algebra

x_1 + x_2 = -\frac{b}{a}, \quad x_1 x_2 = \frac{c}{a}

Sum and product of roots of ax^2 + bx + c = 0

#roots#vieta#polynomials

Completing the Square

Class 10algebra

ax^2 + bx + c = a\left(x + \frac{b}{2a}\right)^2 + \left(c - \frac{b^2}{4a}\right)

Rewriting quadratic into vertex form

#quadratic#factoring

geometry

Distance Formula (2D)

Class 10geometry

d = \sqrt{(x_2-x_1)^2 + (y_2-y_1)^2}

Distance between two points (x1, y1) and (x2, y2)

Interactive Solver:

Point 1 (x₁, y₁)

Point 2 (x₂, y₂)

Distance:5

Midpoint:(1.5, 2)

Slope (m):1.333

#coordinate#distance

Midpoint Formula

Class 10geometry

M = \left(\frac{x_1+x_2}{2}, \frac{y_1+y_2}{2}\right)

Midpoint of a line segment

#coordinate#midpoint

Slope of a Line

Class 10geometry

m = \frac{y_2-y_1}{x_2-x_1} = \tan\theta

Slope of line passing through two points

#coordinate#line#slope

Slope-Intercept Form

Class 10geometry

y = mx + c

Equation of a straight line with slope m and y-intercept c

#coordinate#line

Point-Slope Form

Class 12geometry

y - y_1 = m(x - x_1)

Equation of line passing through (x1, y1) with slope m

#coordinate#line

Standard Circle Equation

Class 12geometry

(x-h)^2 + (y-k)^2 = r^2

Circle with center (h, k) and radius r

#conic#circle

General Parabola Equation

Class 12geometry

y = a(x-h)^2 + k \quad \text{or} \quad (y-k)^2 = 4a(x-h)

Parabola in vertex form

#conic#parabola

Standard Ellipse Equation

Class 12geometry

\frac{(x-h)^2}{a^2} + \frac{(y-k)^2}{b^2} = 1

Ellipse centered at (h, k) with semi-major/minor axes a, b

#conic#ellipse

Standard Hyperbola Equation

Class 12geometry

\frac{(x-h)^2}{a^2} - \frac{(y-k)^2}{b^2} = 1

Horizontal hyperbola centered at (h, k)

#conic#hyperbola

Section Formula (Internal)

Class 10geometry

P = \left(\frac{m x_2 + n x_1}{m+n}, \frac{m y_2 + n y_1}{m+n}\right)

Coordinates of point dividing line segment in ratio m:n

Interactive Solver:

Point A (x₁, y₁)

Point B (x₂, y₂)

Ratio m : n

Point P:(2, 4)

#coordinate#section

Perpendicular Distance from Point to Line

Class 12geometry

d = \frac{|Ax_1 + By_1 + C|}{\sqrt{A^2 + B^2}}

Distance from point (x1, y1) to line Ax + By + C = 0

#coordinate#distance#line

trigonometry

Pythagorean Identity

Class 10trigonometry

\sin^2\theta + \cos^2\theta = 1

Fundamental trigonometric identity relating sine and cosine

#identities#pythagorean

Secant & Tangent Identity

Class 10trigonometry

1 + \tan^2\theta = \sec^2\theta

Pythagorean identity for tangent and secant

#identities#pythagorean

Cosecant & Cotangent Identity

Class 10trigonometry

1 + \cot^2\theta = \csc^2\theta

Pythagorean identity for cotangent and cosecant

#identities#pythagorean

Sine Addition & Subtraction

Class 12trigonometry

\sin(A \pm B) = \sin A \cos B \pm \cos A \sin B

Sine of sum or difference of two angles

#compound#addition

Cosine Addition & Subtraction

Class 12trigonometry

\cos(A \pm B) = \cos A \cos B \mp \sin A \sin B

Cosine of sum or difference of two angles

#compound#addition

Tangent Addition & Subtraction

Class 12trigonometry

\tan(A \pm B) = \frac{\tan A \pm \tan B}{1 \mp \tan A \tan B}

Tangent of sum or difference of two angles

#compound#addition

Double Angle (Sine)

Class 12trigonometry

\sin(2\theta) = 2\sin\theta\cos\theta

Sine of double angle

#double-angle

Double Angle (Cosine)

Class 12trigonometry

\cos(2\theta) = \cos^2\theta - \sin^2\theta = 2\cos^2\theta - 1 = 1 - 2\sin^2\theta

Cosine of double angle formulas

#double-angle

Half Angle Formulas

Class 12trigonometry

\sin\left(\frac{\theta}{2}\right) = \pm\sqrt{\frac{1-\cos\theta}{2}}, \quad \cos\left(\frac{\theta}{2}\right) = \pm\sqrt{\frac{1+\cos\theta}{2}}

Sine and cosine of half angle

#half-angle

Law of Sines

Class 10trigonometry

\frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C} = 2R

Relates sides of a triangle to the sines of its angles

Interactive Triangle Solver (SAS):

Side a

Side b

Angle C (°)

Computed Side c:c = 5.568

#triangles#sines

Law of Cosines

Class 10trigonometry

c^2 = a^2 + b^2 - 2ab\cos C

Relates sides of a triangle to cosine of an angle

Interactive Triangle Solver (SAS):

Side a

Side b

Angle C (°)

Computed Side c:c = 5.568

#triangles#cosines

probability

Permutations Formula

probability

P(n, r) = {}^n P_r = \frac{n!}{(n-r)!}

Number of ordered arrangements of r elements from n

#combinatorics#permutations

Combinations Formula

probability

C(n, r) = {}^n C_r = \binom{n}{r} = \frac{n!}{r!(n-r)!}

Number of unordered selections of r elements from n

#combinatorics#combinations

Addition Rule of Probability

probability

P(A \cup B) = P(A) + P(B) - P(A \cap B)

Probability of union of two events

#probability#union

Multiplication Rule

probability

P(A \cap B) = P(A) \cdot P(B|A)

Probability of simultaneous occurrence of two events

#probability#intersection

Conditional Probability

probability

P(A|B) = \frac{P(A \cap B)}{P(B)} \quad (P(B) > 0)

Probability of event A occurring given event B has occurred

#probability#conditional

Bayes' Theorem

probability

P(A|B) = \frac{P(B|A) \cdot P(A)}{P(B)} = \frac{P(B|A) P(A)}{\sum P(B|A_i) P(A_i)}

Calculates posterior probability based on prior knowledge

#probability#bayes

Binomial Distribution PMF

probability

P(X = k) = \binom{n}{k} p^k (1-p)^{n-k}

Probability of k successes in n independent Bernoulli trials

#distribution#binomial

Poisson Distribution PMF

probability

P(X = k) = \frac{\lambda^k e^{-\lambda}}{k!}

Probability of k events in a fixed interval with average rate λ

#distribution#poisson

Expected Value (Discrete)

probability

E[X] = \sum_{i} x_i \cdot P(X = x_i)

Weighted average of all possible values of discrete random variable

#statistics#mean#expectation

Variance & Standard Deviation

probability

\text{Var}(X) = E[X^2] - (E[X])^2, \quad \sigma = \sqrt{\text{Var}(X)}

Measure of dispersion of a random variable

#statistics#variance

Standard Normal Distribution (PDF)

probability

f(z) = \frac{1}{\sqrt{2\pi}} e^{-z^2/2}, \quad z = \frac{x - \mu}{\sigma}

Probability density function of standard normal variable

#distribution#normal#z-score

mensuration

Circle Area

mensuration

A = \pi r^2

Area of a circle with radius r

#2d#area#circle

Circle Circumference

mensuration

C = 2\pi r

Perimeter of a circle

#2d#perimeter#circle

Triangle Area

mensuration

A = \frac{1}{2}bh

Area of a triangle with base b and height h

#2d#area#triangle

Heron's Formula

mensuration

A = \sqrt{s(s-a)(s-b)(s-c)}

Triangle area from side lengths, s = (a+b+c)/2

#2d#area#triangle

Rectangle Area

mensuration

A = l \times w

Area of a rectangle

#2d#area#rectangle

Trapezium Area

mensuration

A = \frac{1}{2}(a+b)h

Area of a trapezium with parallel sides a, b

#2d#area#trapezium

Sphere Volume

mensuration

V = \frac{4}{3}\pi r^3

Volume of a sphere

#3d#volume#sphere

Sphere Surface Area

mensuration

S = 4\pi r^2

Surface area of a sphere

#3d#surface#sphere

Cylinder Volume

mensuration

V = \pi r^2 h

Volume of a cylinder

#3d#volume#cylinder

Cylinder Surface Area

mensuration

S = 2\pi r(r+h)

Total surface area of a cylinder

#3d#surface#cylinder

Cone Volume

mensuration

V = \frac{1}{3}\pi r^2 h

Volume of a cone

#3d#volume#cone

Cone Curved Surface Area

mensuration

S = \pi r l

Lateral surface area of a cone with slant height l

#3d#surface#cone

Cuboid Volume

mensuration

V = l \times w \times h

Volume of a cuboid

#3d#volume#cuboid

Hemisphere Volume

mensuration

V = \frac{2}{3}\pi r^3

Volume of a hemisphere

#3d#volume#hemisphere

logarithms

Product Rule for Logs

logarithms

\log_b(xy) = \log_b(x) + \log_b(y)

Logarithm of a product equals sum of logarithms

#product#logarithm

Quotient Rule for Logs

logarithms

\log_b\left(\frac{x}{y}\right) = \log_b(x) - \log_b(y)

Logarithm of a quotient equals difference of logarithms

#quotient#logarithm

Power Rule for Logs

logarithms

\log_b(x^k) = k \log_b(x)

Exponent comes out as a multiplier

#power#exponent#logarithm

Change of Base Formula

logarithms

\log_b(x) = \frac{\log_k(x)}{\log_k(b)} = \frac{\ln x}{\ln b} = \frac{\log_{10} x}{\log_{10} b}

Converting logarithm to a different base k

#base#conversion

Identity & Zero Properties

logarithms

\log_b(b) = 1, \quad \log_b(1) = 0

Basic identity properties of logarithms

#identity#logarithm

Inverse Properties

logarithms

b^{\log_b x} = x, \quad \log_b(b^x) = x

Logarithms and exponentials are inverse functions

#inverse#exponential

Natural Log & Euler Constant

logarithms

\ln(x) = \log_e(x), \quad e = \lim_{n \to \infty}\left(1 + \frac{1}{n}\right)^n \approx 2.71828

Definition of natural logarithm and base e

#natural#euler

Exponential Laws

logarithms

a^m \cdot a^n = a^{m+n}, \quad \frac{a^m}{a^n} = a^{m-n}, \quad (a^m)^n = a^{mn}

Fundamental laws of exponent arithmetic

#exponential#powers

Related Formula Sheets

GCSE Maths Formula Sheet A-Level Maths Formula Sheet Edexcel Maths Formula Sheet

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IGCSE Maths Formula Sheet

algebra

Quadratic Formula

Class 10algebra

x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

Roots of a quadratic equation ax^2 + bx + c = 0

#roots#equations#quadratic

Difference of Squares

Class 10algebra

a^2 - b^2 = (a - b)(a + b)

Factoring difference of two squares

#factoring#polynomials

Sum of Cubes

Class 10algebra

a^3 + b^3 = (a + b)(a^2 - ab + b^2)

Factoring sum of two cubes

#factoring#cubes

Difference of Cubes

Class 10algebra

a^3 - b^3 = (a - b)(a^2 + ab + b^2)

Factoring difference of two cubes

#factoring#cubes

Binomial Theorem

Class 12algebra

(x+y)^n = \sum_{k=0}^{n} \binom{n}{k} x^{n-k} y^k

Expansion of a binomial power

#expansion#series#binomial

Arithmetic Progression (nth Term)

Class 10algebra

a_n = a_1 + (n-1)d

nth term of an AP with common difference d

#sequences#ap

Arithmetic Progression (Sum)

Class 10algebra

S_n = \frac{n}{2}(2a_1 + (n-1)d) = \frac{n}{2}(a_1 + a_n)

Sum of first n terms of an AP

#series#ap

Geometric Progression (nth Term)

Class 12algebra

a_n = a_1 r^{n-1}

nth term of a GP with common ratio r

#sequences#gp

Geometric Progression (Sum)

Class 12algebra

S_n = \frac{a_1(1-r^n)}{1-r} \quad (r \neq 1)

Sum of first n terms of a GP

#series#gp

Infinite Geometric Series

Class 12algebra

S_\infty = \frac{a_1}{1-r} \quad (|r| < 1)

Sum of infinite GP when ratio is strictly between -1 and 1

#series#infinite

Vieta's Formulas (Quadratic)

Class 10algebra

x_1 + x_2 = -\frac{b}{a}, \quad x_1 x_2 = \frac{c}{a}

Sum and product of roots of ax^2 + bx + c = 0

#roots#vieta#polynomials

Completing the Square

Class 10algebra

ax^2 + bx + c = a\left(x + \frac{b}{2a}\right)^2 + \left(c - \frac{b^2}{4a}\right)

Rewriting quadratic into vertex form

#quadratic#factoring

geometry

Distance Formula (2D)

Class 10geometry

d = \sqrt{(x_2-x_1)^2 + (y_2-y_1)^2}

Distance between two points (x1, y1) and (x2, y2)

Interactive Solver:

Point 1 (x₁, y₁)

Point 2 (x₂, y₂)

Distance:5

Midpoint:(1.5, 2)

Slope (m):1.333

#coordinate#distance

Midpoint Formula

Class 10geometry

M = \left(\frac{x_1+x_2}{2}, \frac{y_1+y_2}{2}\right)

Midpoint of a line segment

#coordinate#midpoint

Slope of a Line

Class 10geometry

m = \frac{y_2-y_1}{x_2-x_1} = \tan\theta

Slope of line passing through two points

#coordinate#line#slope

Slope-Intercept Form

Class 10geometry

y = mx + c

Equation of a straight line with slope m and y-intercept c

#coordinate#line

Point-Slope Form

Class 12geometry

y - y_1 = m(x - x_1)

Equation of line passing through (x1, y1) with slope m

#coordinate#line

Standard Circle Equation

Class 12geometry

(x-h)^2 + (y-k)^2 = r^2

Circle with center (h, k) and radius r

#conic#circle

General Parabola Equation

Class 12geometry

y = a(x-h)^2 + k \quad \text{or} \quad (y-k)^2 = 4a(x-h)

Parabola in vertex form

#conic#parabola

Standard Ellipse Equation

Class 12geometry

\frac{(x-h)^2}{a^2} + \frac{(y-k)^2}{b^2} = 1

Ellipse centered at (h, k) with semi-major/minor axes a, b

#conic#ellipse

Standard Hyperbola Equation

Class 12geometry

\frac{(x-h)^2}{a^2} - \frac{(y-k)^2}{b^2} = 1

Horizontal hyperbola centered at (h, k)

#conic#hyperbola

Section Formula (Internal)

Class 10geometry

P = \left(\frac{m x_2 + n x_1}{m+n}, \frac{m y_2 + n y_1}{m+n}\right)

Coordinates of point dividing line segment in ratio m:n

Interactive Solver:

Point A (x₁, y₁)

Point B (x₂, y₂)

Ratio m : n

Point P:(2, 4)

#coordinate#section

Perpendicular Distance from Point to Line

Class 12geometry

d = \frac{|Ax_1 + By_1 + C|}{\sqrt{A^2 + B^2}}

Distance from point (x1, y1) to line Ax + By + C = 0

#coordinate#distance#line

trigonometry

Pythagorean Identity

Class 10trigonometry

\sin^2\theta + \cos^2\theta = 1

Fundamental trigonometric identity relating sine and cosine

#identities#pythagorean

Secant & Tangent Identity

Class 10trigonometry

1 + \tan^2\theta = \sec^2\theta

Pythagorean identity for tangent and secant

#identities#pythagorean

Cosecant & Cotangent Identity

Class 10trigonometry

1 + \cot^2\theta = \csc^2\theta

Pythagorean identity for cotangent and cosecant

#identities#pythagorean

Sine Addition & Subtraction

Class 12trigonometry

\sin(A \pm B) = \sin A \cos B \pm \cos A \sin B

Sine of sum or difference of two angles

#compound#addition

Cosine Addition & Subtraction

Class 12trigonometry

\cos(A \pm B) = \cos A \cos B \mp \sin A \sin B

Cosine of sum or difference of two angles

#compound#addition

Tangent Addition & Subtraction

Class 12trigonometry

\tan(A \pm B) = \frac{\tan A \pm \tan B}{1 \mp \tan A \tan B}

Tangent of sum or difference of two angles

#compound#addition

Double Angle (Sine)

Class 12trigonometry

\sin(2\theta) = 2\sin\theta\cos\theta

Sine of double angle

#double-angle

Double Angle (Cosine)

Class 12trigonometry

\cos(2\theta) = \cos^2\theta - \sin^2\theta = 2\cos^2\theta - 1 = 1 - 2\sin^2\theta

Cosine of double angle formulas

#double-angle

Half Angle Formulas

Class 12trigonometry

\sin\left(\frac{\theta}{2}\right) = \pm\sqrt{\frac{1-\cos\theta}{2}}, \quad \cos\left(\frac{\theta}{2}\right) = \pm\sqrt{\frac{1+\cos\theta}{2}}

Sine and cosine of half angle

#half-angle

Law of Sines

Class 10trigonometry

\frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C} = 2R

Relates sides of a triangle to the sines of its angles

Interactive Triangle Solver (SAS):

Side a

Side b

Angle C (°)

Computed Side c:c = 5.568

#triangles#sines

Law of Cosines

Class 10trigonometry

c^2 = a^2 + b^2 - 2ab\cos C

Relates sides of a triangle to cosine of an angle

Interactive Triangle Solver (SAS):

Side a

Side b

Angle C (°)

Computed Side c:c = 5.568

#triangles#cosines

probability

Permutations Formula

probability

P(n, r) = {}^n P_r = \frac{n!}{(n-r)!}

Number of ordered arrangements of r elements from n

#combinatorics#permutations

Combinations Formula

probability

C(n, r) = {}^n C_r = \binom{n}{r} = \frac{n!}{r!(n-r)!}

Number of unordered selections of r elements from n

#combinatorics#combinations

Addition Rule of Probability

probability

P(A \cup B) = P(A) + P(B) - P(A \cap B)

Probability of union of two events

#probability#union

Multiplication Rule

probability

P(A \cap B) = P(A) \cdot P(B|A)

Probability of simultaneous occurrence of two events

#probability#intersection

Conditional Probability

probability

P(A|B) = \frac{P(A \cap B)}{P(B)} \quad (P(B) > 0)

Probability of event A occurring given event B has occurred

#probability#conditional

Bayes' Theorem

probability

P(A|B) = \frac{P(B|A) \cdot P(A)}{P(B)} = \frac{P(B|A) P(A)}{\sum P(B|A_i) P(A_i)}

Calculates posterior probability based on prior knowledge

#probability#bayes

Binomial Distribution PMF

probability

P(X = k) = \binom{n}{k} p^k (1-p)^{n-k}

Probability of k successes in n independent Bernoulli trials

#distribution#binomial

Poisson Distribution PMF

probability

P(X = k) = \frac{\lambda^k e^{-\lambda}}{k!}

Probability of k events in a fixed interval with average rate λ

#distribution#poisson

Expected Value (Discrete)

probability

E[X] = \sum_{i} x_i \cdot P(X = x_i)

Weighted average of all possible values of discrete random variable

#statistics#mean#expectation

Variance & Standard Deviation

probability

\text{Var}(X) = E[X^2] - (E[X])^2, \quad \sigma = \sqrt{\text{Var}(X)}

Measure of dispersion of a random variable

#statistics#variance

Standard Normal Distribution (PDF)

probability

f(z) = \frac{1}{\sqrt{2\pi}} e^{-z^2/2}, \quad z = \frac{x - \mu}{\sigma}

Probability density function of standard normal variable

#distribution#normal#z-score

mensuration

Circle Area

mensuration

A = \pi r^2

Area of a circle with radius r

#2d#area#circle

Circle Circumference

mensuration

C = 2\pi r

Perimeter of a circle

#2d#perimeter#circle

Triangle Area

mensuration

A = \frac{1}{2}bh

Area of a triangle with base b and height h

#2d#area#triangle

Heron's Formula

mensuration

A = \sqrt{s(s-a)(s-b)(s-c)}

Triangle area from side lengths, s = (a+b+c)/2

#2d#area#triangle

Rectangle Area

mensuration

A = l \times w

Area of a rectangle

#2d#area#rectangle

Trapezium Area

mensuration

A = \frac{1}{2}(a+b)h

Area of a trapezium with parallel sides a, b

#2d#area#trapezium

Sphere Volume

mensuration

V = \frac{4}{3}\pi r^3

Volume of a sphere

#3d#volume#sphere

Sphere Surface Area

mensuration

S = 4\pi r^2

Surface area of a sphere

#3d#surface#sphere

Cylinder Volume

mensuration

V = \pi r^2 h

Volume of a cylinder

#3d#volume#cylinder

Cylinder Surface Area

mensuration

S = 2\pi r(r+h)

Total surface area of a cylinder

#3d#surface#cylinder

Cone Volume

mensuration

V = \frac{1}{3}\pi r^2 h

Volume of a cone

#3d#volume#cone

Cone Curved Surface Area

mensuration

S = \pi r l

Lateral surface area of a cone with slant height l

#3d#surface#cone

Cuboid Volume

mensuration

V = l \times w \times h

Volume of a cuboid

#3d#volume#cuboid

Hemisphere Volume

mensuration

V = \frac{2}{3}\pi r^3

Volume of a hemisphere

#3d#volume#hemisphere

logarithms

Product Rule for Logs

logarithms

\log_b(xy) = \log_b(x) + \log_b(y)

Logarithm of a product equals sum of logarithms

#product#logarithm

Quotient Rule for Logs

logarithms

\log_b\left(\frac{x}{y}\right) = \log_b(x) - \log_b(y)

Logarithm of a quotient equals difference of logarithms

#quotient#logarithm

Power Rule for Logs

logarithms

\log_b(x^k) = k \log_b(x)

Exponent comes out as a multiplier

#power#exponent#logarithm

Change of Base Formula

logarithms

\log_b(x) = \frac{\log_k(x)}{\log_k(b)} = \frac{\ln x}{\ln b} = \frac{\log_{10} x}{\log_{10} b}

Converting logarithm to a different base k

#base#conversion

Identity & Zero Properties

logarithms

\log_b(b) = 1, \quad \log_b(1) = 0

Basic identity properties of logarithms

#identity#logarithm

Inverse Properties

logarithms

b^{\log_b x} = x, \quad \log_b(b^x) = x

Logarithms and exponentials are inverse functions

#inverse#exponential

Natural Log & Euler Constant

logarithms

\ln(x) = \log_e(x), \quad e = \lim_{n \to \infty}\left(1 + \frac{1}{n}\right)^n \approx 2.71828

Definition of natural logarithm and base e

#natural#euler

Exponential Laws

logarithms

a^m \cdot a^n = a^{m+n}, \quad \frac{a^m}{a^n} = a^{m-n}, \quad (a^m)^n = a^{mn}

Fundamental laws of exponent arithmetic

#exponential#powers