TeX source:
\begin{array}{rclcl} \mathbb{D} &=& \mathbb{R} \cr \cr -12x\left(x^2-19\right) &=& 24\left(-x^2+10\right) \cr -12x^3+228x &=& -24x^2+240 &\vert& +24x^2-240 \cr -12x^3+24x^2+228x-240 &=& 0 \end{array}