Edexcel ·Mathematics·Cambridge IGCSE Mathematics

Quadratics

14 min read

Solving quadratics by factorising, the quadratic formula, completing the square, and the discriminant.

Solving by factorising

A quadratic $ax^2 + bx + c = 0$ may factorise into two brackets. If the product is zero, one of the factors is zero:

$x^2 - 2x - 15 = 0 \;\Rightarrow\; (x - 5)(x + 3) = 0 \;\Rightarrow\; x = 5 \text{ or } x = -3$

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Edexcel ·Mathematics·Cambridge IGCSE Mathematics

14 min read

Solving quadratics by factorising, the quadratic formula, completing the square, and the discriminant.

A quadratic $ax^2 + bx + c = 0$ may factorise into two brackets. If the product is zero, one of the factors is zero:

$x^2 - 2x - 15 = 0 \;\Rightarrow\; (x - 5)(x + 3) = 0 \;\Rightarrow\; x = 5 \text{ or } x = -3$

Create a free account to read this note in full. Every free account gets 2 complete revision notes — no card needed.