[tex]\bf 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}}
\\\\
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\cfrac{3^2}{3^4}\implies 3^2\cdot 3^{-4}\implies 3^{2-4}\implies 3^{-2}\quad \checkmark
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\cfrac{3^1}{3^3}\implies 3^1\cdot 3^{-3}\implies 3^{1-3}\implies 3^{-2}\quad \checkmark[/tex]