TeX source:
\begin{array}{rclcl} z_1 = x^2 &=& 11 &\vert& \pm\sqrt{} \cr\cr x_{1,2} &=& \pm\sqrt{11} \approx 3{,}32 \cr\cr z_2 = x^2 &=& -8 &\vert& \pm\sqrt{} \cr\cr x_{3,4} &=& \pm\sqrt{-8} \end{array}