Answer
$\int_{2}^{7} (5x^3-4x)~dx$
Work Step by Step
$\int_{a}^{b}f(x)~dx = \lim\limits_{n \to \infty}\Sigma_{i=1}^{n} f(x)~\Delta x$
$\int_{a}^{b}f(x)~dx = \lim\limits_{n \to \infty}\Sigma_{i=1}^{n} [5(x_i^*)^3-4x_i^*]~\Delta x$
In the limit, we can see that the function is $f(x) = 5x^3-4x$
We can write the definite interval:
$\int_{2}^{7} (5x^3-4x)~dx$
