$(1)$ Evaluate $\_([0,1]\backslash$times $[0,2])($x$)/(1+$xy$)$dA$.$

$(2)$ Find the volume of the solid region that lies under the surface

z$=$xe$^($xy$)$ and directly above the region $[0,3]\backslash$times $[0,1].$

$(3)$ Find the absolute maximum and minimum values of f$=2$x$+$

$2$y$-$x$^(2)-$y$^(2)$ on the region $[0,2]\backslash$times $[0,2].$