Rearranging formulae: GCSE Maths revision
Changing the subject means rearranging a formula so a different letter is on its own. Use inverse operations, just like solving equations.
One-step and two-step
Make u the subject of v = u + at
Make r the subject of C = 2πr
Try these questions
Cover the answers and have a go first. Worked solutions are underneath.
Make a the subject of v = u + at
Make x the subject of y = 3x + 2
Make r the subject of A = πr² (r > 0)
Make b the subject of a = (b + c) / 2
Common mistakes
- Only dividing one term on the right.
- Forgetting to square-root both sides when r² is the subject.
Answers and working
Frequently asked questions
What does “subject” mean?
The subject is the letter on its own on one side of the formula, usually the left.
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