Fundamental Theorem of Calculus Integration I've been trying to work on this problem for an hour and for some reason I'm apparently not inputting the correct answer. The problem was to find the derivative of $\int_{x^5}^{x^7} (2t-1)^3 dt$ and I used F.T.O.C to get $-(2x^5-1)^3+(2x^7-1)^3$, but it keeps saying it wasn't correct, all I did was separate the problem into 2 bounds from $x^5$ to 0 and 0 to $x^7$ and reversed the $x^5$ to 0 one making it negative like F.T.O.C guides. What am I doing wrong and what is the correct answer?

If $F(t)$ is a primitive of $(2t-1)^3$ (you don't need to compute it), then
$$\frac{d}{dx} \int_{x^5}^{x^7}(2t-1)^3 dt = \frac{d}{dx} (F(x^7)-F(x^5)) = (2x^7-1)^3 \cdot 7x^6 - (2x^5-1)^3 \cdot 5x^4$$
where the last equality follows from using the chain rule.
