Express (4-5i)(-5-5i) in the form a+bi , where a and b are integers and i^2=-1.
(4-5i)(-5-5i) =
- ( 4 - 5i)(5 + 5i) =
- [ 4*5 + 4*5i -5*5i - 5i*5i ] =
- [ 20 - 5i - 25i^2 ] =
- [20 - 5i + 25 ] =
- 45 + 5i
