TeX Quellcode:

\begin{array}{rclcll}0 &=& \dfrac{\sqrt{x+7}}{2}+77 &\vert& -\dfrac{\sqrt{x+7}}{2} \\-\dfrac{\sqrt{x+7}}{2} &=& 77 &\vert& \cdot (-2) \\\sqrt{x+7} &=& -154 &\vert& ()^2 \\x+7 &=& 23.716 &\vert& -7 \\x &=& 23.709\;\in\;\mathbb{D} \end{array}