TeX Quellcode:

\begin{array}{rclcll}(1-k)\left[x^2-(1+k)\pi^2\right] &=& 0 &\vert& :(1-k) \\x^2-(1+k)\pi^2 &=& 0 &\vert& +(1+k)\pi^2 \\x^2 &=& \left(1+k\right)\pi^2 &\vert& \pm\sqrt{} \\x_{3,4} &=& \pm\sqrt{\left(1+k\right)\pi^2}\end{array}