[tex]\bf a^{-{ n}} \implies \cfrac{1}{a^{ n}}\qquad \qquad
\cfrac{1}{a^{ n}}\implies a^{-{ n}}
\\ \quad \\
% negative exponential denominator
a^{{ n}} \implies \cfrac{1}{a^{- n}}
\qquad \qquad
\cfrac{1}{a^{- n}}\implies \cfrac{1}{\frac{1}{a^{ n}}}\implies a^{{ n}} \\\\
-----------------------------\\\\
\cfrac{4xy}{mn^5}\implies \cfrac{4xy}{1}\cdot \cfrac{1}{m^1}\cdot \cfrac{1}{n^5}\implies 4xym^{-1}n^{-5}[/tex]
notice, all you do is, move the factor from the bottom to the top, or from the top to the bottom, and the sign changes, from negative to positive or the other way around, is all there's on that
