Consider the following.
$$\int x\sqrt{x - 20} \, dx$$
The integral can be evaluated using integration by parts with the following choice of u.
$$u = x$$
Determine du, dv, and v.
$$du = (1) \, dx$$
$$dv = (\sqrt{x-20}) \, dx$$
$$v = \frac{2}{3}(x-20)^{(\frac{3}{2})}$$
Evaluate the integral. (Remember the constant of integration.)
$$\int x\sqrt{x - 20} \, dx = $$
