[tex]\bf a^{-{ n}} \implies \cfrac{1}{a^{ n}}\qquad \qquad
\cfrac{1}{a^{-n}}\implies a^{{ n}}\\\\
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\cfrac{b^{-2}}{ab^{-5}}\implies \cfrac{b^{-2}\cdot b^{+5}}{a}\implies \cfrac{b^{-2+5}}{a}\implies \cfrac{b^3}{a}[/tex]
