1. The problem statement, all variables and given/known data Let I := [a,b] and let f: I→ℝ be continuous on I. Also let J := [c,d] and let u: J→ℝ be differentiable on J and satisfy u(J) contained in I. Show that if G: J→ℝ is defined by G(x) :=∫u(x)af for x in J, then G'(x) = (f o u)(x)u'(x) for all x in J. 2. The attempt at a solution I am not sure what theorem to use in this situation. I am thinking that the product and composition of differentiable functions means that G'(x) exists....but I don't believe that will help me in this situation. Any ideas as to how i should start this one?