top of page
Rearranging (changing the subject of) a formula uses inverse operations to isolate a chosen variable, including cases where the subject appears twice. It's examined right across GCSE and iGCSE Maths. Work through it free on eClassroom, with clear worked examples and instantly-marked questions that build your confidence for the exam.
How you do it
Do the same thing to both sides to peel away everything around the subject, undoing operations in reverse order. If the subject appears twice, collect those terms on one side, factorise it out, then divide.
Before you start
Everything here rests on solving linear equations. You will lean on this again for changing the subject in science and at A-Level. Assessed at Foundation and Higher tier.
What you learn
To rearrange a formula is to make a different letter the subject — the letter on its own. We use inverse operations to undo what is being done to that letter, doing the same to both sides, just like solving an equation. The subject is the letter by itself on one side. When two operations act on the letter, undo them in reverse order — undo the +/− first, then the ×/÷. The course works through inverse operations, two-step rearranging and division and brackets. Every section has instant-feedback practice questions matched to Edexcel iGCSE 4MA1 and the other major GCSE boards, and the course finishes with full exam-style questions you mark yourself.
Related Topics
Rearranging Formulae is a Algebra topic in the GCSE syllabus, covered here at Foundation tier. It runs to 3 concepts, each followed by a check, with 2 worked examples along the way. Related topics students usually take next include Sequences, Simplifying Expressions, Simultaneous Equations, Substitution and Algebraic Fractions. The Algebra revision engine gives you as many extra questions as you want, tracked on your skill tree.
Still need help with a topic?
bottom of page