[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}}
\\\\
-------------------------------\\\\
\cfrac{-10a^2b^4}{5a^{-9}b^{-5}}\implies \cfrac{-10}{5}\cdot \cfrac{a^2b^4}{a^{-9}b^{-5}}\implies \cfrac{-2}{1}\cdot \cfrac{a^2a^9b^4b^5}{1}
\\\\\\
-2a^{2+9}b^{4+5}\implies -2a^{11}b^9[/tex]
