Well if
then
.
But by DeMoivre's Theorem.
So .
Now equate real and imaginary parts.
Thanks,
Iam having troubles with this one too...
Determine all solutions for: z^4 + 3z^2 -4=0
The ans is +-1,+-2i
I got too,
r^4 (cos 4theta + i sin 4theta) + 3r^2(cos 2theta + i sin 2 theta) = 4 (cos 0 + 2pi k + i sin 0 +2pi k).
but don't know what to do from here,solving for R ,I get R=1,R=-4 ? and theta = 1/3 pi k ?