Let x represent radius of circle.
We have been given that the height of a cylinder is twice the radius of its base. So height of cylinder would be [tex]2x[/tex].
Now we will use volume of cylinder formula to our given problem.
[tex]V=\pi r^2h[/tex], where,
r = Radius of base of cylinder,
h = Height of cylinder.
Upon substituting our given values, we will get:
[tex]V=\pi\cdot x^2\cdot 2x[/tex]
[tex]V=2x^3\pi[/tex]
Therefore, our required volume expression would be [tex]2x^3\pi[/tex].