Partual derivatives

6. (20 points) f ( x , y ) = (A) Let Its= 2x4 + 2y2 + 8xy -3. Find all the local maxima, local minima and saddle points of f by the second derivative test. (B) Find the absolute maxima and minima of f(x, y) = 4x2 - 8x + 2y2 - 8y + 3 on the closed triangular plate bounded by x = 0, y = 2, y = 2x