Paper 1 · Complex Numbers ⏱ Tested in 1 exam question since 2019 Lesson 6 of 7

LCOL Complex Numbers 6: Solving Quadratic Equations

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You’ll learn

  • Spot that a quadratic in z with i mentioned will have complex roots
  • Solve it with the −b formula (page 20): z = (−b ± √(b² − 4ac)) / 2a
  • Handle the negative under the square root using i² = −1

Formula used

z = (−b ± √(b² − 4ac)) / 2a

On page 20 of the log tables — read it off, don’t memorise.

Most recent exam questions

  • 2019 P1 Q2(b)

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