(b) Evaluate the line integral | (3x -2vy + z)ds, where C is the portion of the curve x = t + bt, y = f and z=bt -2t from the point (2+2b, 4, 2b-4) to the point (4+4b, 16, 4b- 8). Here b is a constant. Give your answer in terms of b. (6 marks) (c) Consider the force field F =[yz -ysin(xy)]i+[xz -xsin(xy)]j+xyk. Find a potential function o( x, y, z.) for the vector function F.IIf C is any path from point P (1, 0, 1) to point Q (4, nt/4, 3), evaluate the work done W by the force to push an object from point P to Q: W = F.dr C