TeX Quellcode:

\begin{array}{crclll} & \sqrt{9x^2-42x+49}+3x &=& 7 \\\\& \sqrt{\left(3x-7\right)^2}+3x &=& 7 \\& \left\vert 3x-7\right\vert +3x &=& 7 \end{array}