Concept · 4 steps · NESA MA4-EQU-C-01

Solving and Verifying Equations by Substitution

Solving an equation is only half the job. The other half — the one that wins back lost marks and lets you trust your own working — is verifying: putting your answer back in to prove it really fits.

1Where it comes fromWhat "verify" really means — sub the answer back and watch both sides land on the same number. 2How to do itSolve, then substitute to check. A generator, step reveal, and your own check. 3Where it gets trickySubstitute into both sides — why a near-miss value never balances. 4Out in the wildCatch other people's mistakes, and work the verification backwards.

← This concept rests on

Solving Linear Equations Up to Two Steps
Substituting into Expressions

→ It unlocks

Solving Quadratic Equations
Applying Pythagoras' Theorem