how to change negative exponents

Here is a number of other examples.

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

How to change negative exponents

$$\boxed{\
\left( \dfrac{a}{b} \right)^{-n}
=\left( \dfrac{b}{a} \right)^{n}
\ }$$

Example:

$$a=2 \quad b=1\quad n=3\\\\
\left( \dfrac{2}{1} \right)^{-3}
=2^{-3}
=\left( \dfrac{1}{2} \right)^{3}
=\dfrac{1}{2^3}$$