Question 1411

Complex Numbers
2011 Paper 1 Question 10 Variant

Question

Do not use a graphic calculator in answering this question.
(i)
The roots of the equation z2=8i{z^2 = 8 \mathrm{i}} are z1{z_1} and z2.{z_2.} Find z1{z_1} and z2{z_2} in cartesian form x+iy,{x+\mathrm{i}y,} showing your working.
[4]
(ii)
Hence, or otherwise, find in cartesian form the roots w1{w_1} and w2{w_2} of the equation
w24w+(42i)=0.w^2 - 4 w + {\left( \textstyle 4 - 2 \mathrm{i} \right)}=0.
[3]

Answer