Exercise 13.5.3 Find ow and at ow for w = f(u), given u = s. t, and then evaluate them for f(u) = u3 + 3u, t = 1 and s = 2. Exercise 13.5.4 Find w and w for w = f(u), given u = s2 + t2, and then evaluate them for f(u) = us + 3u , t = 1 and s = 2