Let f(x, y) = 2y2 – x². Compute the following: (a) Find the gradient f(x, y). Give your answer using the standard basis vectors i, j. Use symbolic notation and fractions where needed. Vf(x, y) = (b) Find the directional derivative Du f(1, 2) of f at the point (1, 2) in the direction of the vector u = i + j. Dᵤf(1,2)= (c) Give the direction of the fastest rate of increase of f at the point P(1,2). Give your answer as a unit vector using the standard basis vectors i, j. Use symbolic notation and fractions where needed. Direction of fastest increase of f at P is given by: (d) Give the maximal value of the directional derivative of f at P(1,2). Answer =