Hello

I'm having a bit of trouble with the following:

Prove that if complex number z != -1 and modulus of the z is 1, then z can be represented as z = (1 + xi) / (1 - xi), where x is a real number.

What I got so far:

z = a + bi

a*a + b*b = 1

z = sqrt(1 - b*b) + bi

Now I would guess, I have to convert that last line to the required form of z = (1 + xi) / (1 - xi), but I simply can't figure this out.

Thanks

EDIT: Solved it just a few hours after posting it