Question 1417

Complex Numbers
2017 Paper 1 Question 8 Variant

Question

Do not use a calculator in answering this question.
(a)
Find the roots of the equation
z2(12i)2z+(2+4i)=0,z^2 \left(1 - 2 \mathrm{i}\right) - 2 z + (2 + 4 \mathrm{i})=0,
giving your answers in cartesian form a+ib.{a+\mathrm{i}b.}
[3]
(bi)
Given that ω=1+i,{\omega=- 1 + \mathrm{i},} find ω2,{\omega^2,} ω3{\omega^3} and ω4{\omega^4} in cartesian form.
Given also that
ω4+pω3+23ω2+qω+82=0,\omega^4 + p \omega^3 + 23 \omega^2 + q \omega + 82=0,
where p{p} and q{q} are real, find p{p} and q.{q.}
[4]
(bii)
Using the values of p{p} and q{q} in part (bii), express
ω4+pω3+23ω2+qω+82\omega^4 + p \omega^3 + 23 \omega^2 + q \omega + 82
as the product of two quadratic factors.
[3]

Answer