The Math Meridian
Back to Complex Numbers, Counting and Proof

Complex numbers: add, subtract, multiply and divide

Questions at easy, medium and hard levels. Pick a level and get a fresh set every time, with instant feedback.

Useful for: IB Math AA HL IB Math AI HL AP® Precalculus

Learn it i² = −1. Add and subtract real and imaginary parts separately. Multiply like binomials, replacing i² with −1. To divide, multiply top and bottom by the conjugate of the bottom (a + bi → a − bi).

Example: (3 + 2i)(1 − 4i).

  1. 3 − 12i + 2i − 8i².
  2. = 3 − 10i + 8 = 11 − 10i.

Loading questions…