Answer
$\left(b^4\right)^{-3}=b^{-12}=\dfrac{1}{b^{12}}$
Work Step by Step
RECALL:
(i) The power rule of exponents states that: $\left(a^{m}\right)^n=a^{mn}$.
(ii) The negative-exponent rule states that: $a^{-m} = \dfrac{1}{a^m}$ and $\dfrac{1}{a^{-m}}=a^m$ where $a \ne 0$.
Use the power rule to find:
$\left(b^4\right)^{-3}=b^{4(-3)}=b^{-12}$
Use the negative-exponent rule to find:
$b^{-12} = \dfrac{1}{b^{12}}$
