Answer
$36 \pi$
Work Step by Step
We need to use the shell model as follows:
$V=\int_p^{q} (2 \pi) \cdot (\space radius \space of \space shell) ( height \space of \space Shell) \space dx$
$ \implies V= \int_0^{3} (2 \pi) \cdot (x)[\dfrac{9x}{(x^3+9)^{1/2}}) dx$
Suppose $a=x^3+9 \implies da=3x^2dx$
Now, $V=2 \pi \times \int_{9}^{36} [3 a^{-1/2} da$
or, $=6 \pi \times [2 a^{1/2}]_{9}^{36}$
or, $=36 \pi$
