# How do you simplify -(xy^-1)/(9z^-2) and write it using only positive exponents?

Apr 8, 2018

$- \frac{x {z}^{2}}{9 y}$

#### Explanation:

Recall the law of indices about negative indices: ${x}^{-} m = \frac{1}{x} ^ m$

$- \frac{x \textcolor{b l u e}{{y}^{-} 1}}{9 \textcolor{m a \ge n t a}{{z}^{-} 2}}$

$= - \frac{x \textcolor{m a \ge n t a}{{z}^{2}}}{9 \textcolor{b l u e}{{y}^{1}}}$

When you move the base and the index from the numerator to the denominator or from the denominator to the numerator, the sign changes.