Hi,

I am an economist so I know some maths but a lot of it is way beyond me. I joined because I trying to find an answer to a simple question in calculus, which I can't seem to find anywhere.

The question is: how do you differentiate the integral of a composite function? Specifically, if $\displaystyle F(k(j))= \int \! g(k(j)) \, \mathrm{d}j $ what is $\displaystyle \frac{dF}{dk}$?

The closest thing to an answer I could find was Leinbniz's rule, which suggested the answer should be $\displaystyle \int \! \frac{dg}{dk} \, \mathrm{d}j$, but the answer I should get (according to someone else's notes) is just $\displaystyle \frac{dg}{dk} $, as if the integral isn't there.

Hope someone can help. Thanks.