(a) Let z = f(x, y) and x = u 2 − v 3 , y = 2uv + v 2 . Find ∂f ∂v at the point (u, v) = (1, 0) when f1(1, 1) = 3 and f2(1, 1) = −4.

 (b) Let z = x 2 + 3xy + 7y 3 . Compute all possible second order partial derivatives of f. 

(c)  Explain what geometrically gradient means

(d)Explain what geometrically directional derivative means