Ans: C
$\begin{array}{cl}
& (3a)^2\cdot a^3 \\
= & 9a^2 \cdot a^3 \\
= & 9a^{2+3} \\
= & 9a^5
\end{array}$
$\begin{array}{cl}
& (3a)^2\cdot a^3 \\
= & 9a^2 \cdot a^3 \\
= & 9a^{2+3} \\
= & 9a^5
\end{array}$
Resources for HKDSE Mathematics
Resources for HKDSE Mathematics
