Algebra · Formulae & rearranging
Chapter 1 · 4
The idea
Rearranging formulae
Why changing the subject is solving-an-equation in disguise, why operations must be undone in reverse order (onion peeling), and how fractions, squares and roots come apart.
A full journey — read it, play with it, work it, then earn real exam marks. Everything stays on the timeline below.
In this lesson — start anywhere
Algebra · Formulae & rearranging
Rearranging formulae
Why changing the subject is solving-an-equation in disguise, why operations must be undone in reverse order (onion peeling), and how fractions, squares and roots come apart.
Why it works
The same balance game
Every formula you'll ever meet is stored in ONE arrangement — , — and questions constantly want another. "Make the subject" means: rewrite the formula as with appearing exactly once, alone. It's the same balance game as solving an equation — the only difference is that letters, not numbers, ride along. Every move is an inverse operation applied to both whole sides.Peel the onion
In , the was multiplied by then had subtracted. Undo in reverse order — last operation first:Keep reading — free
The rest of the explanation, plus 2 worked examples you step through move by move.
Start freeTakes a minute — no card.