#22

20. R = F(t, u) where t = t(w, x, y, z), u = u(w, x, y, z) 21-26 Use the Chain Rule to find the indicated partial derivative 21. z = x+ + xy, x = s + 2t - u, y = stu; az dz dz when s = 4, t = 2, u = 1 as' at' du 22 . T U u = pqvr, v = pvqr; 2u + v aT aT aT ap' aq' ar when p = 2, q = 1, r = 4 23. w = xy + yz + zx, x = rcos0, y = rsin0, z = re; when r = 2, 0 = TT/2 ar