3)
[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{-9}{2x^5}\implies \cfrac{-3^2}{2x^5}\implies \cfrac{-3^2}{1}\cdot \cfrac{1}{2}\cdot \cfrac{1}{x^5}\implies -\cfrac{1}{3^{-2}}\cdot 2^{-1}\cdot x^{-5}
\\\\\\
-\cfrac{2^{-1}x^{-5}}{3^{-2}}[/tex]
4)
[tex]\bf 5^{-2}+5^0\implies \cfrac{1}{5^2}+1\implies \cfrac{1}{25}+1\implies \cfrac{1+25}{25}\implies \cfrac{26}{25}[/tex]