TeX Quellcode:

\begin{array}{rclcc} 5x^2-15x-20 &=& 0 \cr x_{1,2} &=& \dfrac{-(-15) \pm \sqrt{\left(-15\right)^2-4\cdot 5\cdot \left(-20\right)}}{2\cdot 5} \cr\cr x_{1,2} &=& \dfrac{15 \pm \sqrt{225+400}}{10} \cr\cr x_{1,2} &=& \dfrac{15 \pm \sqrt{625}}{10} \cr\cr x_{1,2} &=& \dfrac{15\pm 25}{10} \cr\cr\cr x_1 &=& \dfrac{15+25}{10} = \dfrac{40}{10} = 4 \cr\cr x_2 &=& \dfrac{15-25}{10} = -\dfrac{10}{10} = -1 \cr\cr \mathbb{L} &=& \{-1;4\} \end{array}