Concept · 4 steps · NESA MA4-EQU-C-01

Solving Quadratic Equations

When x is squared, you undo it with a square root. It starts as the side of a square and ends up being the very thing that makes Pythagoras work — one idea, doing a lot of jobs.

1Where it comes fromx² is the area of a square. Set the area, read off the side — that's the square root. 2How to do itSolve x² = k by taking the square root of both sides (with the ±), plus a practice generator. 3Where it gets trickyThere are usually two answers — and a negative right-hand side has none. Don't drop the ±. 4Out in the wildFind a square's side from its area, working backwards — the seed of Pythagoras.

← This concept rests on

Solving Linear Equations Up to Two Steps
Square Roots

→ It unlocks

Identifying and Defining Pythagoras' Theorem
Applying Pythagoras' Theorem