Answer:
[tex] - \frac{18}{ {b}^{4} } [/tex]
Step-by-step explanation:
[tex] - 18b {}^{ - 4} [/tex]
express b^-4 with a positive exponent using:
[tex]a {}^{ - n} = \frac{1}{ {a}^{n} } [/tex]
[tex] - 18 \frac{1}{ {b}^{4} } [/tex]
[tex] - \frac{18}{ {b}^{4} } [/tex]
