TeX Quellcode:

\begin{matrix} \left|\dfrac 25 \begin{pmatrix}-20\cr25\cr-9\end{pmatrix}\right| &=& \left|\begin{pmatrix}-8 \cr10\cr-\frac{18}{5}\end{pmatrix}\right| \cr\cr &=& \sqrt{{\left(-8\right)}^2+{10}^2+{\left(-\dfrac{18}{5}\right)}^2 } \cr &=& \sqrt{\dfrac{4424}{25}} &\approx & 13{,}30 \end{matrix}