Zjist�te $\sup_{z \in M}f(z),\, \inf_{z \in M}f(z)$ a
vy�et�ete, zda $f$ t�t� hodnoty na $M$ nab�v�.
$$
f(x,y) = (x + y)e^{-2x-3y} \qquad\qquad M = \{(x,y) \in \Bbb
R^2; \, x \geq 0, y \geq 0\}  \qquad\qquad (\text{25 bod�})
$$
