lim (x.y)(0,0) x+y x*-y2 does not exist. (a) Show that (b) Find the slope of the surface z = xy cos(xy) at the point (1/2, 1) along y-direction. (c) The temperature distribution on a metal plate in the xy-plane is given by T(x, y) = xye*Y. Find the rate at which temperature changes if you start at the point (1,2) and move right parallel to the x-axis.