TeX source:
\begin{array}{rclcl}u_1 = x^2 &=& 16 &\vert& \pm\sqrt{} \\x_{1,2} &=& \pm 4 \\\\u_2 = x^2 &=& 1 &\vert& \pm\sqrt{} \\x_{3,4} &=& \pm 1 \\\\\mathbb{L} &=& \left\{-4;-1; 1; 4\right\}\end{array}