Rearranging a formula means making one letter the subject


Rearrange a + d = c + b to make c the subject:

c = a + d – b

Six steps that apply to rearranging formulae:

o       Remove any square root signs by squaring both sides

o       Deal with fractions by cross-multiplying to get everything on one line (the top line)

o       Multiply out any brackets

o       Collect up all subject terms on one side of the = sign, and all non-subject terms on the other side

o       Combine any like terms. You want to reach the point where your formula is Ax = B, where x is what you want to make the subject. You may need to factorise in order to get x times something on the left-hand side

o       Divide both sides by A, leaving x alone on the left-hand side and everything else on the right-hand side of the = sign

If you end up with x2 on the left-hand side instead of just x, then you need to take the square root of both sides, to obtain just x as the subject of the formula.

Rearranging formulae revision questions