Let f(x, y) = 2x^3 − 6xy + 3y^2 be a function defined on
xy-plane
(a) Find first and second partial derivatives of.
(b) Determine the local extreme points of f (max., min., saddle
points) if there are any.
(c) Find the absolute max. and absolute min. values of f over
the closed region bounded by the lines x = 2, y = 0, and y = x