Hi to all, 1. The problem statement, all variables and given/known data Evaluate the surface integral of the vector F=xi+yj+zk over that portion of the surface x=xy+1 which covers the square 0≤x≤1 , 0≤y≤1 in the xy plane 2. Relevant equations ∫∫F.ndσ n=∇g/|∇g| maybe transformation to the volume integral 3. The attempt at a solution g(x,y,z)=xy+1-z n=∇g/|∇g|=(yi+xj-k)/√(y2+x2+1) Plugging into integral, i finally got ∫∫((xy-1)/(√(y2+x2+1))) dxdy both x and y are from 0 to 1. But i could not take this integral without help of a computer. Since this is from a book's ordinary question i don't think it needs such a treatment. I think i could transform the surface integral into a volume integral but there is not a well defined volume that can be used. So, i stuck at this point. Thanks.