Chapter 5 - Exponents and Polynomials - Chapter 5 Review Problem Set - Page 231: 56

$\dfrac{1}{4}$

Using $\dfrac{1}{a^{-x}}=a^x$, the given expression, $ \dfrac{1}{\left(\dfrac{1}{4}\right)^{-1}} ,$ simplifies to \begin{array}{l}\require{cancel} \left(\dfrac{1}{4}\right)^{1} \\\\= \dfrac{1}{4} .\end{array}