TeX Quellcode:

\begin{array}{rcll}f\left(\dfrac{249}{32}\right) &=& 20\sqrt{2\cdot\dfrac{249}{32}-15}-15 \\\\&=& 20\sqrt{\dfrac{9}{16}}-15 \\&=& 20\cdot\dfrac{3}{4}-15 \\&=& 0 \\\end{array}