30. let f: {(x, y) e r :x> 0,y> 0) r be given by f(x, y) =x y 3 tan alue of g(x, y) = xy) + yfy (x, y) f(x, y) (a) changes with x but not with y (c) changes wit

30. Let f: {(x, y) e R :x> 0,y> 0) R be given by f(x, y) =x y 3 tan alue of g(x, y) = xY) + yfy (x, y) f(x, y) (a) changes with x but not with y (c) changes with X and also with y (6) changes with y but not with x Ud) Neither changes with x nor with y