Three Ways to Solve a Quadratic Equation
Solve quadratic equations by factoring, the quadratic formula and completing the square, with worked examples and tips on choosing a method.
Author: <span>math_person</span>
Standard Deviation and Variance Explained Step by Step
What standard deviation measures, how to calculate it for a population or a sample, why samples divide by n − 1, and a full worked example.
Sine, Cosine and Tangent Explained (SOHCAHTOA and the Unit Circle)
Learn what sin, cos and tan mean in right triangles and on the unit circle, the exact values for 30°, 45° and 60°, and the ASTC sign rule.
The Pythagorean Theorem with Worked Examples
Use a² + b² = c² to find any side of a right triangle, check for right angles, and find distances on a grid. Worked examples and common mistakes.
Permutations vs Combinations: When Order Matters
Learn the difference between permutations and combinations, the nPr and nCr formulas, and how to use them for lotteries, teams and passwords.
The Normal Distribution and Z-Scores Made Simple
Understand the bell curve, the 68–95–99.7 rule, z-scores and how to find normal probabilities, with worked examples on test scores and heights.
Logarithms Explained for Beginners
What a logarithm is, how it undoes an exponent, the three log laws, the change-of-base formula and how to solve exponential equations.
Limits Explained: Substitution, Factoring and L'Hôpital's Rule
What a limit is, how to evaluate one by substitution, factoring or L'Hôpital's rule, and how to handle limits at infinity. Clear worked examples.
Integration for Beginners: Antiderivatives and Area
Understand integration as reverse differentiation and as area under a curve. Learn the power rule, definite integrals and integration by parts.
How to Solve Simultaneous Equations: Substitution vs Elimination
Solve pairs of simultaneous equations by substitution or elimination, see what the answer means on a graph, and spot when there is no solution.