8.6 Rearranging formulae — Practise with help

1. $x=4$.
2. Dividing by 4.

If an answer differs, revisit Section 9.1 for solving equations and Section 1.4 for inverse operations.

Undo the operation affecting the required subject, in reverse order.

Use the inverse operation on both sides to isolate the named letter.

$x=y-7$.

Undo the operation affecting the required subject, in reverse order.

Use the inverse operation on both sides to isolate the named letter.

$x=\frac{y}{4}$. Check: $4(y/4)=y$.

Undo the operation affecting the required subject, in reverse order.

Use the inverse operation on both sides to isolate the named letter.

$b=A-a$.

Undo the operation affecting the required subject, in reverse order.

Use the inverse operation on both sides to isolate the named letter.

$r=\frac{C}{2}$.

Undo the operation affecting the required subject, in reverse order.

Use the inverse operation on both sides to isolate the named letter.

$h=\frac{2V}{b}$.

Undo the operation affecting the required subject, in reverse order.

Use the inverse operation on both sides to isolate the named letter.

$t=s+9$.

Undo the operation affecting the required subject, in reverse order.

Use the inverse operation on both sides to isolate the named letter.

$w=\frac{P-2l}{2}$.

Undo the addition of $4$ on both sides.

Subtract $4$ from both sides of $x=y+4$.

$x=x$ — start with the given equation $x=y+4$.

$x-4=y$ — subtract $4$ from both sides.

$y=x-4$ — write the subject on the left.