CAIE A-Level Mathematics 3.9.6 Complex numbers

CAIE A-Level Mathematics 3.9.6 Complex numbers
Cambridge International AS & A Level Mathematics 9709 syllabus for exams in 2028, 2029 and 20302028–2030

Practise finding exact square roots of complex numbers in Cartesian or polar form, showing the equations that determine both roots.

How this is tested

  • square x+iy and equate real and imaginary parts to form two equations
  • eliminate x or y to find exact Cartesian square roots in conjugate-sign pairs
  • halve the argument and root the modulus when square roots are requested in polar form

Question 5

[Maximum number: 5]

The square roots of 145i-1-4 \sqrt{5} \mathrm{i} can be expressed in the Cartesian form x+iy, where x and y are real and exact.

By first forming a quartic equation in x or y, find the square roots of 145i-1-4 \sqrt{5} \mathrm{i} in exact Cartesian form.