if x-iy=underroot [(a-ib)/(c-id)]

prove that(x^{2}+y^{2})^{2}= a^{2}+b^{2}/c^{2}+d2

just remember the comjugate of a complex number can be obtained by changing i to -i

then multiply the complex number with its conjugate

and i^{2} = -1