For the vector field F(x, y, z) = (2y — 1) 7+ (z² + 2xz)J+2xyk - the line integral over the curve C: x² + y² = 9 at z = 0 yields f F · dr = −18π. $ State Stokes' theorem and then verify Stokes' theorem in this case by calcu- lating the surface integral over the paraboloid z = 9 - (x² + y²) above the xy-plane.