[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{3}{250}\qquad
\begin{cases}
250=2\cdot 5\cdot 5\cdot 5\\
\qquad 2\cdot 5^3
\end{cases}\implies \cfrac{3}{5^3\cdot 2}\implies \cfrac{1}{5^3}\cdot \cfrac{3}{2}
\\\\\\
5^{-3}\cdot \cfrac{3}{2}\implies (5^{-1})^3\cdot \cfrac{3}{2}[/tex]
