[tex]\bf ~\hspace{7em}\textit{negative exponents} \\\\ a^{-n} \implies \cfrac{1}{a^n} ~\hspace{4.5em} a^n\implies \cfrac{1}{a^{-n}} ~\hspace{4.5em} \cfrac{a^n}{a^m}\implies a^na^{-m}\implies a^{n-m} \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ (3a)(a^{-3})\implies 3a\cdot \cfrac{1}{a^3}\implies \cfrac{3a}{a^3}\implies \cfrac{3~~\begin{matrix} a \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~}{aa~~\begin{matrix} a \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~}\implies \cfrac{3}{a^2}[/tex]
