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MA11-04 Maths Watch

Rearranging Harder Formulae (Subject Appears Twice, or Under a Power/Root)

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In this lesson

In this video you'll learn about rearranging harder formulae for GCSE Maths, with worked examples and the mistakes examiners report. By the end you'll be able to rearrange a formula to change the subject when that subject appears twice, or when the subject is under a power or a root, by factorising or by squaring/rooting both sides.

What it covers

  1. 0:41 Straightforward rearranging undoes one operation at a time, and that is exactly what breaks here
  2. 4:07 Your letter can also sit in one place and still be out of reach, because it is squared
  3. 5:22 Flip that round now, so the root is wrapped around the letter you want
  4. 8:45 Exam technique
  5. 11:49 What's next

Key words

For: Edexcel IGCSE 4MA1, OCR GCSE J560, Cambridge IGCSE 0580

On the specification

BoardSpecStatement
Edexcel IGCSE 4MA1H2.3AUnderstand the process of manipulating formulae or equations to change the subject, to include cases where the subject may appear twice or a power of the subject occurs
OCR GCSE J5606.02cRearrange formulae to change the subject, where the subject appears once only.
Cambridge IGCSE 0580E2.5Construct expressions, equations and formulas.
For teachers

This GCSE Maths lesson teaches rearranging harder formulae (subject appears twice, or under a power/root). By the end, students should be able to rearrange a formula to change the subject when that subject appears twice, or when the subject is under a power or a root, by factorising or by squaring/rooting both sides. It works through three worked examples and the mistakes examiners report.