TeX source:
\begin{array}{rclcl} 0 &=& 14x^2+42x+14 &\vert& : 14 \cr 0 &=& x^2+3x+1 &\vert& \text{p-q-Formel} \cr x_{3,4} &=& -\dfrac{3}{2} \pm \sqrt{\left(\dfrac{3}{2}\right)^2-1} \cr\cr x_{3,4} &=& -\dfrac{3}{2} \pm \sqrt{\dfrac{5}{4}} \cr\cr x_3 &=& -\dfrac{3}{2}+\dfrac{\sqrt{5}}{2} = \dfrac{-3+\sqrt{5}}{2} \approx -0{,}38 \cr\cr x_4 &=& -\dfrac{3}{2}-\dfrac{\sqrt{5}}{2} = \dfrac{-3-\sqrt{5}}{2} \approx -2{,}62 \cr\cr \mathbb{L} &=& \left\{\dfrac{-3-\sqrt{5}}{2};\dfrac{-3+\sqrt{5}}{2};0;1\right\} \end{array}