Under construction still

(testing that math works here) $$\begin{align*} \frac{d}{dx} \left( \int_{0}^{x} f(u) , du \right) &= f(x) \ \frac{d}{dx} \left( \int_{g(x)}^{h(x)} f(u) , du \right) &= f(h(x))h'(x) - f(g(x))g'(x) \end{align*}$$