Foundation and Higher · solving equations

Whatever you do to one side —
do to the other.

but why?

an equation is —

BALANCE

Two sides that weigh
exactly the same.

worked example · two steps

Solve for x

3x−4=11

3x=15

x=5

add 4 to both sides

↓ + 4

divide both sides by 3

↓ ÷ 3

1. Start: 3x − 4 = 11.

2. Add 4 to both sides.

3. 3x = 15.

4. Divide both sides by 3.

✓ x = 5

the two you'll use most

+ e.g. x + 5

↔

− subtract 5

× e.g. 3x

↔

÷ divide by 3

the one rule

Inverse operation —
on both sides.

Most lost marks come from
forgetting the other side.

The
Maths Habit

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