#### Answer

\[{y^,} = 24{x^{5/3}}\]

#### Work Step by Step

\[\begin{gathered}
y = 9{x^{8/3}} \hfill \\
Differentiate \hfill \\
{y^,} = \frac{d}{{dx}}\,\,\left[ {9{x^{8/3}}} \right] \hfill \\
{y^,} = 9\frac{d}{{dx}}\,\,\left[ {{x^{8/3}}} \right] \hfill \\
Use\,\,the\,\,formula \hfill \\
\,\,\frac{d}{{dx}}\,\,\left[ {{x^n}} \right] = n{x^{n - 1}} \hfill \\
Then \hfill \\
{y^,} = 9\,\left( {\frac{8}{3}} \right){x^{8/3 - 1}} \hfill \\
{y^,} = 24{x^{5/3}} \hfill \\
\hfill \\
\end{gathered} \]