Paper 1 · Complex Numbers ⏱ Tested in 5 exam questions since 2016 Lesson 8 of 17

Complex Numbers 8 – Quadratic equations

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You’ll learn

  • Solve quadratics with negative discriminants using the −b formula
  • Use the conjugate-pair theorem: real coefficients mean complex roots come in pairs
  • Find an unknown coefficient via z² − (sum)z + (product) = 0 or by subbing the known root
  • Apply the −b formula when coefficients are non-real, where conjugate pairing fails

Most recent exam questions

  • 2024 P1 Q2(a)
  • 2023 P1 Q3(b) — deferred
  • 2023 P1 Q4(a)
  • 2019 P1 Q5(a)
  • 2016 P1 Q1(a)

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