So using the fundamental theorem of calculus, I know that with a being a constant, the derivative of $\int_{a}^{x} f(t)dt$ is just f(x). But what if the upper limit of integration is not x, but instead with something like 5x+2? or x squared?
So what would be the derivative of $\int_{a}^{5x+2} f(t)dt$ (a will always be a constant)?