Answer:
You can use the exponential rule where
[tex](n^x)^y=n^{xy}[/tex]
Therefore,
[tex](a^3)^{-2}=a^{3*(-2)}=a^{-6}[/tex]
[tex]\\ \rm\leadsto (a^3)^{-2}[/tex]
[tex]\\ \rm\leadsto a^{-6}[/tex]
[tex]\\ \rm\leadsto \dfrac{1}{a^6}[/tex]
