Chapter 7 - Exponents and Exponential Functions - 7-1 Zero and Negative Exponents - Practice and Problem-Solving Exercises - Page 421: 11

$\frac{1}{25}$

$(-5)^{-2}$ = $\frac{1}{(-5)^{2}}$ = $\frac{1}{25}$ Whenever there is a negative exponent, we should place the term under a 1 to make the exponent positive. Then we evaluate the expression. In this instance, the answer is $\frac{1}{25}$