Bonsoir,
[tex]\left\{\begin{array}{ccc}z_1+z_2=-2\\z_1*z_2=10\end{array}\right.\\\\\left\{\begin{array}{ccc}z_2=-2-z_1\\z_1*(-2-z_1)=10\end{array}\right.\\\\\left\{\begin{array}{ccc}z_2=-2-z_1\\z_1^2+2z_1+10=0\end{array}\right.\\\\\Delta=4-4*10=-36=(6i)^2\\[/tex]
[tex]\left\{\begin{array}{ccc}z_1=\dfrac{-2+6i}{2} \\z_2=-2-\dfrac{-2+6i}{2}\end{array}\right.\\\\\left\{\begin{array}{ccc}z_1=-1+3i \\z_2=-1-3i\end{array}\right.\\\\ou\\\left\{\begin{array}{ccc}z_1=\dfrac{-2-6i}{2} \\z_2=-2-\dfrac{-2-6i}{2}\end{array}\right.\\\\\left\{\begin{array}{ccc}z_1=-1+3i \\z_2=-1+3i\end{array}\right.\\\\[/tex]
