Answer Happy

please show the solution of 3-2 and 3-3
3. Let f(x, y) = 8x³ - 12xy + y³. 1.(5%) Find the tangent plane of the surface z = f(x, y) at (1,4). 3-2.(5%) In what direction does f(x, y) have minimum rate of change at (1,4)? 3-3. (10%) Find the local maximum, local minimum and saddle points of f(x, y).