Finding derivative of function defined as integral

In this math example, we are given a function defined as an integral from zero to x, where the integrand is in terms of t. We use the fundamental theorem of calculus to determine that the derivative of the function is simply the function from the integrand with the variables replaced with x's. We then use the derivative and evaluate it at a given value by replacing each of the x's with that value and simplifying. We then find the 2nd derivative by using the power rule of derivatives on the 1st derivative. We evaluate the second derivative at a given value and simplify.