TeX Quellcode:

\begin{array}{rclcll}0 &=& -2\sqrt{x+15}+7 &\vert& +2\sqrt{x+15} \\2\sqrt{x+15} &=& 7 &\vert& :2 \\ \\\sqrt{x+15} &=& \dfrac{7}{2} &\vert& ()^2 \\ \\x+15 &=& \dfrac{49}{4} &\vert& -15 \\ \\x &=& -\dfrac{11}{4}\;\in\;\mathbb{D}\end{array}