TeX Quellcode:

\begin{array}{rcl}f'_{xx}(x,y) &=& -\dfrac{5}{9}\sin(x)\cdot e^{\sin(x)+\sin(y)}+\dfrac{5}{9}\cos(x)e^{\sin(x)+\sin(y)}\cdot\cos(x) \\\\&=& -\dfrac{5}{9}\sin(x)e^{\sin(x)+\sin(y)}+\dfrac{5}{9}\cos^2(x)e^{\sin(x)+\sin(y)} \\\\&=& \dfrac{5}{9}e^{\sin(x)+\sin(y)}\left(-\sin(x)+\cos^2(x)\right)\end{array}