How to square imaginary numbers?
Can someone please explain to me how to do question 8b and z^-1 for 9? Thanks!
Can someone please explain to me how to do question 8b and z^-1 for 9? Thanks!
1 Answer
Feb 28, 2018
Explanation:
If
(a+b)^2 = a^2+2ab+b^2
So we find:
(2-i)^2 = 2^2+2(2)(-i)+(-i)^2 = 4-4i-1 = 3-4i
Note that
(3+2i)^(-1) = 1/(3+2i)
color(white)((3+2i)^(-1)) = (3-2i)/((3-2i)(3+2i))
color(white)((3+2i)^(-1)) = (3-2i)/(3^2-(2i)^2)
color(white)((3+2i)^(-1)) = (3-2i)/(9+4)
color(white)((3+2i)^(-1)) = (3-2i)/13
color(white)((3+2i)^(-1)) = 3/13-2/13 i