Question

Need help understanding this problem (1-i)^2, next(1-i)(1-i) = 1-i-i+i^2 =1-i-i+(-1), the ans. is -2i, and I don't see it?

Answer 1

This is an application of the algebraic identity
(a-b)^2=a^2-2ab+b^2

Now replace a=1, b=i, you get
(1-i)^2=1^2-2(1)(i)+i^2
=1-2i+i^2
But i is a special number such that i^2=-1, so the net result is
(1-i)^2 = 1-2i-1 = -2i after putting 1-1=0

Answer 2

thankyou, I need to work on this one.

Answer 3

You're welcome! :)