Quadratic Equations
A quadratic equation has the form ax² + bx + c = 0. Every GCSE student is expected to solve these by factorising. Completing the square and the quadratic formula are Higher-tier methods, used when an equation won't factorise neatly:
x = (-b ± √(b² - 4ac)) / 2a
Worked example
Solve x² - 5x + 6 = 0 by factorising: (x - 2)(x - 3) = 0, so x = 2 or x = 3.