Given --(1) Given surface is plane --(2)
Note that the plane (2) is perpendicular to xy-plane.So,we shall not project the given surface on xy-plane. Hence,in the present problem, we project surface S on xz-plane.Then,clearly,the projection of surface S is the rectangle on xz-plane bounded by z=0 to z=4 and x=0 to x=3.
Therefore,Required surface integral= --(3) where n =unit normal vector to surface --(4)
Therefore,from (4),So --(5)
Using (5) and (6),the required surface integral =
= on simplification.