Basisbewerkingen gemengd (a+bi)

Bereken

\((-3-4i) \cdot (-5-7i)\)

\((-3-4i) \cdot (-5-7i)= 15+21i +20 i+28i^2 = 15+21i +20 i-28= \color{red}{15-28}\color{blue}{+21i +20i}=\color{red}{-13}\color{blue}{+41i}\)