5. There is a function h, where h f(x) = x B - 3 g(x) = x + Dx = gof. You already know about the chain rule: h'(x) = g'(f(x))'f'(x). Verify, by taking the derivatives using your ABCD, whether the chain rule applies on second derivatives, too. (Tip: change the "prime" to "double prime" in the equation above.)