where F(x,y,z) = yi - xj - 2k and S is the
surface of the paraboloid z = x2 + y2 (with upward
orientation) within the cylinder x2 + y2 = 1.
2. Use Stokes' Theorem to compute 
where S is the top half of a sphere of radius 3 centered at the origin
with upward orientation and F(x,y,z) = zi + yj - xk.