how do you turn a negative variable exponet to a postive one

Thanks Heureka,

Try looking at this post:)

http://web2.0calc.com/questions/indices-especially-negative-indices

how do you turn a negative variable exponet to a postive one

$$\small{\text{
$
\begin{array}{c}
a^{-x}=\dfrac{1}{a^x} \\\\
\dfrac{1}{a^{-x}}=a^x
\end{array}
$
}}$$