Paper 1 · Indices and Logs ⏱ Tested in 2 exam questions since 2021 Lesson 6 of 8

Indices and Logs 6 – Quadratic Equations 1

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You’ll learn

  • Spot the quadratic in disguise when an equation has both a²ˣ and aˣ terms
  • Substitute y = aˣ so a²ˣ becomes y², then factorise the quadratic
  • Back-substitute each y by matching bases (2ˣ = 8 = 2³ ⇒ x = 3)
  • Reject y ≤ 0 solutions because aˣ is always positive

Most recent exam questions

  • 2025 P1 Q2(b)(ii) — deferred
  • 2021 P1 Q3(b)(ii)

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