[tex]\bf ~\hspace{7em}\textit{negative exponents}
\\\\
a^{-n} \implies \cfrac{1}{a^n}
~\hspace{4.5em}
a^n\implies \cfrac{1}{a^{-n}}
~\hspace{4.5em}
\cfrac{a^n}{a^m}\implies a^na^{-m}\implies a^{n-m}
\\\\[-0.35em]
\rule{34em}{0.25pt}\\\\
\cfrac{2^{y+1}}{2^y}\implies 2^{y+1}\cdot 2^{-y}\implies 2^{(y+1)-y}\implies 2^{1}\implies 2[/tex]
