TeX Quellcode:
\begin{array}{rclcl} 0 &=& \dfrac{a-1}{3}x^2-a &\vert& -\dfrac{a-1}{3}x^2 \cr\cr -\dfrac{a-1}{3}x^2 &=& -a &\vert& \cdot (-3) \cr\cr (a-1)x^2 &=& 3a &\vert& :(a-1) \cr x^2 &=& \dfrac{3a}{a-1} \cr\cr x_{1,2} &=& \pm \sqrt{\dfrac{3a}{a-1}} \end{array}