Answer
$\frac{1}{b^n}$
Work Step by Step
This problem tests your understanding of the Negative-Exponent Rule.
According to the Negative-Exponent Rule, when a non-zero number is raised to a negative exponent, the result is the reciprocal of the number raised to the absolute value of the given negative exponent. Since the absolute value of any negative number is positive, we just remove the minus from the negative exponent, making it positive.
For example, $2^{-2}=\frac{1}{2^2}=\frac{1}{4}$.