TeX source:
\begin{array}{crclcl} & x^2+9x &=& 0 \cr & x(x+9) &=& 0 \cr \text{Faktor 1:} & x_1 &=& 0 \cr\cr \text{Faktor 2:} & x_2+9 &=& 0 \cr & x_2 &=& -9 \cr\cr & \mathbb{L} &=& \{-9;0\} \end{array}