TeX source:
\begin{array}{rclcl} 4x^2-69 &=& -5+2x(8+2x) \cr 4x^2-69 &=& -5+16x+4x^2 & \vert & -4x^2+5 \cr -64 &=& 16x & \vert & :16 \cr x &=& -4 \cr\cr \mathbb{L} &=& \{-4\} \end{array}