Calculus Facts: Derivative of an Integral
mathmistakes.info › facts › CalculusFactsThe first thing to notice about the fundamental theorem of calculus is that the variable of differentiation appears as the upper limit of integration in the integral: Think about it for a moment. Unless the variable x appears in either (or both) of the limits of integration, the result of the definite integral will not involve x, and so the derivative of that definite integral will be zero.
Leibniz integral rule - Wikipedia
https://en.wikipedia.org/wiki/Leibniz_integral_ruleWe first prove the case of constant limits of integration a and b. We use Fubini's theorem to change the order of integration. For every x and h, such that h>0 and both x and x+h are within [x0,x1], we have: Note that the integrals at hand are well defined since is continuous at the closed rectangle and thus also uniformly continuous there; thus its integrals by either dt or dx are continuous in the ot…