Consider the following function f, point P, and unit vector u. a. Compute the gradient of f and evaluate it at P. b. Find the unit vector in the direction of maximum increase of fat P. c. Find the rate of change of the function in the direction of maximum increase at P. d. Find the directional derivative at P in the direction of the given vector. f(x, y,z) = xy + yz + xz + 9; P(9, - 9,8); 0, VZ a. Vf(x,y,z) = Vf(9, - 9,8) = b. The unit vector in the direction of maximum increase of f at P is (Type exact answers.) c. The rate of change of the function in the direction of maximum increase at P is (Type an exact answer.) d. The directional derivative at P in the direction of the given vector is (Type an exact answer.)