Answer
$-\frac{1}{b^{4}}$
Work Step by Step
According to the negative exponent rule, $a^{-n}=\frac{1}{a^{n}}$.
Therefore, $-b^{-4}=\frac{-1}{b^{4}}=-\frac{1}{b^{4}}$.
Recall that the base of the exponent is $b$ and not $-b$.
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