2. Let f(x, y) = al-y. (a) Let A = {(x, y) ER' : x' ty'

2. Let = x' y'. (a) Let A = { (x, y) R2 : + Y2 9}. Does f (x, y) have a global maximum/minimum on A? If yes, find them all. (b) Does have a global maximum/minimum on R2?