GCSE · Formulae & rearranging

Changing the subject when it appears twiceExam-style questions

Why a subject that appears twice must be collected and FACTORISED out, how clearing a fraction first exposes both copies, and the four-step routine that untangles any of these.

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11 questions · GCSE (Higher) level · mark scheme and worked solution on each · no sign-up to try

DifficultyAllLevel 3Level 4Level 5
  1. 1
    Make xx the subject of   y=3x+2x−4\;y = \dfrac{3x + 2}{x - 4}
    Level 5 · 3 marksTry it
  2. 2
    Make pp the subject of   p−q=pq\;p - q = pq
    Level 5 · 3 marksTry it
  3. 3
    y=5x−1x+3y = \dfrac{5x - 1}{x + 3}

    (a) Make xx the subject.

    (b) Hence find the value of xx when y=4y = 4
    Level 5 · 4 marksTry it
  4. 4
    Make xx the subject of   T=a+xx\;T = \sqrt{\dfrac{a + x}{x}}

    where xx and TT are positive.
    Level 5 · 4 marksTry it
  5. 5
    Make xx the subject of   v=u−2xx+5\;v = \dfrac{u - 2x}{x + 5}
    Level 5 · 4 marksTry it

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