Answer:
-a^5/(8b^7)
Step-by-step explanation:
The applicable rules of exponents are ...
(a^b)(a^c) = a^(b+c)
(a^b)^c = a^(bc)
a^-b = 1/a^b
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[tex](-2ab^{-5})(4a^{-2}b)^{-2}=(-2ab^{-5})(4^{-2}a^{-2(-2)}b^{-2})\\\\=\dfrac{-2}{16}a^{1+4}b^{-5-2}=\boxed{-\dfrac{a^5}{8b^7}}[/tex]
