TeX Quellcode:

\begin{array}{rclll}\dfrac{x+21}{2}-4+\dfrac{1}{x} &=& 7 &\vert & -7 \cr\cr\dfrac{x}{2}+\dfrac{21}{2}-11+\dfrac{1}{x} &=& 0 &\vert & \cdot x \cr\cr\dfrac{1}{2}x^2-\dfrac{1}{2}x+1 &=& 0 &\vert& \cdot 2 \cr x^2-x+2 &=& 0 &\vert& \text{p-q-Formel} \cr x_{1,2} &=& \dfrac{1}{2}\pm\sqrt{\left(-\dfrac{1}{2}\right)^2-2} \cr x_{1,2} &=& \dfrac{1}{2}\pm\sqrt{-\dfrac{7}{4}} \end{array}