Evaluate the surface integral.

${}_S(x^2+y^2+z^2)ds$

$S$ is the part of the cylinder $x^2+y^2=4$ that lies between the planes $z=0$ and $z=3,$ together with its top and bottom disks

Evaluate the surface integral.

${}_{S}xzdS,S$ is the boundary of the region enclosed by the cylinder $y^2+z^2=9$ and the planes $x=0$ and $x+y=4$