TeX Quellcode:
\begin{array}{rcl} f(x) &=& \dfrac12 x^2 +4x-7 \cr\cr &=& \dfrac12 \left(x^2 +8x-14 \right) \cr\cr &=& \dfrac12 (x^2 +2 \cdot 4x +4^2 -4^2 -14) \cr\cr &=& \dfrac12 (x^2 +2 \cdot 4x+4^2-30) \cr\cr &=& \dfrac12 (x+4)^2 -15 \cr\cr &=& \dfrac12\left( (x+4)^2 -30\right) \end{array}