Calculating the Imaginary Part of (1-2i)^2-i

[Anood]

How can i find The imaginary part of (1-2i)^2-i.

This is what i have done so far:
(1-2i)^2 (1-2i)^-i

=(1-4i+4)(1-2i)^-i

 

[neutrino]

Use the polar form of 1-2i.