4. (2 credit _) More Short Answer Questions. Here are more short answers questions involving the gradient. Minimal justification is necessary for full credit. Suppose that, over a certain region of space, a function measuring electric potential is given by V(x, y, z) = 5x2 - 3xy - ryz (all distances measured in meters). (a) Compute VV (0, 1, 3) - the gradient of V at the point (0, 1, 3). VV (0, 1, 3) = (b) Which direction measures the rate of steepest decrease of electric potential at (0, 1, 3)? Give your answer as a unit vector. (c) What is the maximum rate of change of V at the point (0, 1, 3)? Hint: Your answer should be a scalar, with units of volts per meter. You don't have to include units on your answer . (d) A particle moves in the direction of the vector v = itj -k. At the point (0, 1, 3), what is the rate of change of V in this direction? Hint: Your answer should be a scalar, with units of volts per meter. You don't have to include units on your