TeX source:
\begin{array}{rclcl}z_1 = y^2 &=& \dfrac{-1+\sqrt{17}}{2} &\vert& \pm\sqrt{} \\y_{1,2} &=&\pm\sqrt{\dfrac{-1+\sqrt{17}}{2}} \approx\pm 1{,}25 \;\in\;\mathbb{D}\\\\z_2 = y^2 &=& \dfrac{-1-\sqrt{17}}{2} &\vert& \pm\sqrt{} \\y_{3,4} &=& \pm\sqrt{\dfrac{-1-\sqrt{17}}{2}}\end{array}