[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}}
\\\\
-------------------------------[/tex]
[tex]\bf \cfrac{\stackrel{\textit{bacteria's volume}}{1.3\times 10^{15}}}{\stackrel{\textit{planet's surface area}}{5.2\times 10^{14}}}\implies \cfrac{1.3\times 10^{15}\times 10^{-14}}{5.2}\implies \cfrac{1.3\times 10^{15-14}}{5.2}
\\\\\\
\cfrac{1.3\times 10}{5.2}\implies \cfrac{13}{5.2}\implies \cfrac{\frac{13}{1}}{\frac{52}{10}}\implies \cfrac{13}{1}\cdot \cfrac{10}{52}\implies \cfrac{130}{52}
\\\\\\
\cfrac{5}{2}\implies 2\frac{1}{2}[/tex]
