[tex] \bf ~~~~~~~~~~~~\textit{negative exponents}
\\\\
a^{-n} \implies \cfrac{1}{a^n}
\qquad \qquad
\cfrac{1}{a^n}\implies a^{-n}
\qquad \qquad
a^n\implies \cfrac{1}{a^{-n}}
\\\\[-0.35em]
\rule{34em}{0.25pt}\\\\
\cfrac{3}{3^3}\implies \cfrac{3^1}{3^3}\implies 3^1\cdot 3^{-3}\implies 3^{1-3}\implies 3^{-2}\implies \cfrac{1}{3^2}\implies \cfrac{1}{9} [/tex]