Module et argument d'un nombre complexe

$|z\times z'| = |z|\times |z'|$

$|\dfrac{z}{z'}| = \dfrac{|z|}{|z'|}$

$|z^n| = |z|^n$

$|\bar z| = |z|$

$|-z|=|z|.$

$\arg(z \times z') = \arg(z) + \arg(z’) [2\pi]$

$\arg\left(\dfrac{z}{z'}\right) = \arg(z) - \arg(z’)[2\pi]$

$\arg(z^n) = n \arg(z)[2\pi]$

$\arg(\bar z) = -\arg(z)[2\pi]$

$\arg(-z) =\pi+\arg(z)[2\pi].$