TeX Quellcode:

\begin{array}{rcl} \displaystyle\int x\cdot \dfrac{1}{\cos^2(x)}\, dx &=& x \cdot \tan(x) - \displaystyle\int 1 \cdot \tan (x) \, dx \cr\cr &=& x \cdot \tan(x) - \left(-\ln\left|\cos(x)\right| \right)+c \cr\cr &=& x \cdot \tan(x) + \ln \left| \cos(x) \right|+c \cr \end{array}