Answer:
24 √2
Step-by-step explanation:
The largest square factor under the radical is $9$. This gives us the factorization $\sqrt{18} = \sqrt 9 \cdot \sqrt 2$. Thus
\begin{align*}
8\sqrt{18} &= 8(\sqrt 9\cdot \sqrt 2) \\
&= 8\cdot 3\sqrt 2 \\
&= \boxed{24\sqrt 2}.
\end{align*}