This is revisiting areas and volumes, but now you have an improper integral. Note that, by unbounded, they mean the region extends to infinity in the x direction. If the area in part (a) is unbounded, that just means that you should discover the
improper integral diverges.
This is one of the many examples of a region with an infinite area, yet, when it is rotated around an axis, it creates a solid with a finite volume. Weird, huh?
You may find it helpful to use u sub first. It is not unheard of to use u sub to change an integral into a form that can then be solved by Integration by parts. In cases like that, I use a different variable other than u so as not to
confuse it with the u in integration by parts.
For example, try letting t equal square root of x, and compute dt. Do a t substitution, then you should find that the dt integral you created is an integration by parts problem.