Cost Function. Suppose the cost to manufacture a product is given by 2 f(x,y) = ex\" The domain of f(x,y) is O the set of all points (x,y) in the xy-plane where y 2 0 O the set of all points (x,y) in the xy-plane O the set of all points (x,y) in the xy-plane where x 2 0 0 none of the other answers Q the set of all points (x,y) in the xy-plane where x 2 0 and y 2 0