Chapter 1 - Introduction to Algebraic Expressions - 1.7 Multiplication and Division of Real Numbers - 1.7 Exercise Set - Page 58: 100

$-1$

The given expression, $ -1 $ is equivalent to $\dfrac{-1}{1}$. To find its reciprocal, interchange the numerator and the denominator. Hence, the reciprocal is \begin{array}{l} \dfrac{1}{-1} \\\\= -\dfrac{1}{1} \\\\= -1 .\end{array}