TeX source:
\begin{array}{crclcl} & \mathbb{D} &=& \mathbb{R} \cr\cr & \dfrac{x^3}{8} &=& x^2+2x-16 & \vert & \cdot 8 \cr\cr & x^3 &=& 8x^2+16x-128 & \vert & -x^3 \cr & 0 &=& -x^3+8x^2+16x-128 & \vert & \cdot (-1) \cr & 0 &=& x^3-8x^2-16x+128 \end{array}