TeX source:
\begin{array}{rclcl} -\dfrac{x}{16}(-32x+64)-x &=& 2x^2-5x \cr 2x^2-4x-x &=& 2x^2-5x \cr 2x^2-5x &=& 2x^2-5x & \vert & -2x^2+5x \cr 0 &=& 0 \cr \cr \mathbb{L} &=& \mathbb{R} \end{array}