2.2.1

Rearranging Formulae

Test yourself

Rearranging Formulae

When rearranging a formula make sure that anything you do to one side of the equation you also do to the other side. To make x the subject of the
equation 3x - 9y = 4x - 24:

Illustrative background for Subtract 4x from both sidesIllustrative background for Subtract 4x from both sides ?? "content

Subtract 4x from both sides

  • We do this so that all the x terms are on one side.
Illustrative background for Add 9y to both sidesIllustrative background for Add 9y to both sides ?? "content

Add 9y to both sides

  • We do this so that all the y terms are on the other side.
Illustrative background for Multiply both sides by (-1)Illustrative background for Multiply both sides by (-1) ?? "content

Multiply both sides by (-1)

  • We have -x but we want x so we must multiply by -1.

Rearranging Formulae

If you square one side of the equation you have to square the other side of the equation too.

Illustrative background for Square rootsIllustrative background for Square roots ?? "content

Square roots

  • To simplify a square root we can square both sides.
Illustrative background for Square rootsIllustrative background for Square roots ?? "content

Square roots

  • If we square root an equation, we need to add a ± sign.
    • Both +5 and -5 solve the equation x² = 25

Jump to other topics

1Numbers

2Equations, Formulae & Identities

3Sequences, Functions & Graphs

4Geometry

5Vectors & Transformation Geometry

6Statistics & Probability

Unlock your full potential with Seneca Premium

  • Unlimited access to 10,000+ open-ended exam questions

  • Mini-mock exams based on your study history

  • Unlock 800+ premium courses & e-books

Get started with Seneca Premium