Suppose that over a certain region of space the electrical potential v is given by the following equation. v(x, y, z) = 4x2 − 2xy + xyz (a) find the rate of change of the potential at p(2, 4, 4) in the direction of the vector v = i + j − k. $$ correct: your answer is correct. (b) in which direction does v change most rapidly at p? $$ correct: your answer is correct. (c) what is the maximum rate of change at p?