Rearranging Formulae
Maths: Edexcel IGCSE Higher, topic 2.2.1
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:
Write out the equation
Subtract 4x from both sides
- We do this so that all the x terms are on one side.
Add 9y to both sides
- We do this so that all the y terms are on the other side.
Multiply both sides by (-1)
- We have -x but we want x so we must multiply by -1.
Now x is the subject of the equation
Rearranging Formulae
If you square one side of the equation you have to square the other side of the equation too.
Square roots
- To simplify a square root we can square both sides.
Square roots
- If we square root an equation, we need to add a ± sign.
- Both +5 and -5 solve the equation x² = 25
Test yourself on Rearranging Formulae
Which of these is the solution to the equation:
2x - 4 = 6Which of these is the solution to the equation:
4y - 4 = 6What are the solutions to the √25?
How can you simplify a square root?
What can this equation be simplified to so that it doesn't contain square roots?
√a + 4 = (4a - 7)