Find the total differential. z = e"* tan(y) dz = Need Help? Read It /5 Points] DETAILS LARCALC12 13.4.039.MI. Use the function to show that f (0, 0) and f (0, 0) both exist, but that f is not differentiable at (0, 0). F(x , y ) = x ty (x, y) = (0, 0) (x, y) = (0, 0) F (0, 0) = f (0, 0) =[ Along the line y=X (x, y) + (0, 0) Along the curve y = x (x, 1) - (0. 0) = O fis continuous at (0, 0) O f is not continuous at (0, 0) Need Help? Read It Watch it Master It -/1 Points] DETAILS LARCALC12 13.6.004. Use Theorem 13.9 to find the directional derivative of the function at P in the direction of the unit vector u = cos di + sin # j. F( x , V ) = 7x + y' P(2, 0), 8 = - Need Help? Read It /1 Points] DETAILS LARCALC12 13.6.008. Find the directional derivative of the function at Pin the direction of v. Ax, y ) = x - y' , p( 4, 3 ), v = V/2 (i+ 1) Need Help? Read It /1 Points] DETAILS LARCALC12 13.6.012. Use Theorem 13.9 to find the directional derivative of the function at P in the direction of PQ. (Give your answer correct to 2 decimal places.) ((x, y) = cos(x + y), P(0. *). (= 0)