Lösung 3.1:1e

A suitable first step can be to work out the square term, (2−i)2, with the help of the square rule:

(2−i)2=22−22i+i2=4−4i+i2=4−4i−1=3−4i

After that, we calculate the remaining product:

(1+i)(3−4i)=13−14i+i3−i4i=3−4i+3i−4i2=3+(−4+3)i−4(−1)=3−i+4=7−i