TeX source:
\begin{array}{rclcl} x^2+2x+2 &=& 0 \cr x_{1,2} &=& -\dfrac{2}{2} \pm \sqrt{\left(\dfrac{2}{2}\right)^2-2} \cr x_{1,2} &=& -1 \pm \sqrt{1-2} \cr x_{1,2} &=& -1 \pm \sqrt{-1} \end{array}