Question 1410b

Complex Numbers
2010 Paper 2 Question 1 Variant

Question

(a)
Solve the equation x28x+20=0.{x^2 - 8 x + 20=0.}
[2]
(b)
One root of the equation
x4+9x3+30x2+ax+b=0,x^4 + 9 x^3 + 30 x^2 + ax + b=0,
where a{a} and b{b} are real, is x=3i.{x=- 3 - \mathrm{i}.}
Find the values of a{a} and b{b} and the other roots.
[5]

Answer