Rearranging a formula means making one letter the subject

Example

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 x^{2 }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

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