Question

(1+i) (1-i)la putera -1

Answer 1

$i^{2}=-1.$ . Aplicam formula :$(a+b)(a-b)=a^2- b^2.deci.[(1+i)(1-i)]^-1=[1^2-(i)^2]^-1=$$[1-(-1)]^-1=(1+1)^-1= \frac{1}{2}$. infinal
s-a. aplicat formula; $a^-1= \frac{1}{a}.$