TeX Quellcode:

\begin{array}{rclll} \dfrac{z^2-4}{z^3+3z} &=& 0 &\vert& \cdot\left(z^3+3z\right) \cr z^2-4 &=& 0 &\vert& +4 \cr z^2 &=& 4 &\vert& \pm\sqrt{} \cr z^2 &=& \pm\sqrt{4} \cr\cr z_{1} &=& 2 \in\mathbb{D} \cr z_{2} &=& -2 \in\mathbb{D} \end{array}