Chapter 5 - Exponents and Polynomials - 5.6 - Integral Exponents and Scientific Notation - Problem Set 5.6 - Page 223: 5

$\dfrac{2}{3}$

Using $a^{-x}=\dfrac{1}{a^x}$ or $\dfrac{1}{a^{-x}}=a^x$ and the laws of exponents, the given expression, $ \left( \dfrac{3}{2} \right)^{-1} ,$ is equivalent to \begin{array}{l}\require{cancel} \dfrac{3^{-1}}{2^{-1}} \\\\= \dfrac{2}{3} .\end{array}