Chapter 7 - Exponents and Exponential Functions - 7-1 Zero and Negative Exponents - Practice and Problem-Solving Exercises - Page 417: 19

$\frac{1}{2.25}$

We want to simplify: $1.5^{-2}$ The negative exponent rule states that for every nonzero number $a$ and integer $n$, $a^{-n}=\frac{1}{a^n}$. We use this to rewrite the expression as $\frac{1}{1.5^2}$. Next, we must simplify the power in the denominator: $\frac{1}{1.5\times1.5}=\frac{1}{2.25}$.