# How do you simplify (9)^- 3 and write as a fraction?

${9}^{-} 3 = \frac{1}{9} ^ 3 = \frac{1}{729}$.
In general, ${a}^{-} n$, for any positive integer $n$, is equal to $\frac{1}{a} ^ n$, provided $a \ne 0$