TeX Quellcode:

\begin{array}{rclcl} 0 &=& 3x^2+(6-6r)x-12r \cr 0 &=& 3x^2+6(1-r)x-12r &\vert& :3 \cr 0 &=& x^2+2(1-r)x-4r &\vert& \text{p-q-Formel} \cr x_{1,2} &=& -\dfrac{2(1-r)}{2} \pm \sqrt{(1-r)^2+4r} \cr x_{1,2} &=& -(1-r) \pm \sqrt{1-2r+r^2+4r} \cr x_{1,2} &=& -1+r \pm \sqrt{r^2+2r+1} \cr x_{1,2} &=& -1+r \pm \sqrt{(r+1)^2} \cr\cr x_1 &=& -1+r+r+1 = 2r \cr x_2 &=& -1+r-r-1 = -2 \end{array}