Exercise 9

For \(f(x, y, z) = x^2yz - xyz^3\) at point \(P(2, -1, 1)\) with vector \(u = \langle 0, 4/5, -3/5 \rangle\): (a) Find the gradient of f. (b) Evaluate the gradient at the point P. (c) Find the rate of change of f at P in the direction of the vector u.