(1 point) Suppose that f(x, y, z) = xyz xyz is a function of three variables. 1. Find the gradient of f(x, y, z). Answer: Vf(x, y, z) = - 2. Evaluate the gradient at the point P(2, -2, -1). Answer: Vf(2, -2, 1) = 3. Find the rate of change of f(x, y, z) at P in the direction of the vector u = (0, 1, 3). Answer: Du f(2, 2, 1) = (1 point) Find the gradient of the function f(x, y, z) = z ln(xy), at the point (1, e, -1) V(1, e, 1) =