9514 1404 393
Answer:
-x^4/(2y)
Explanation:
Perhaps you want to simplify ...

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The applicable rules of exponents are ...
(a^b)/(a^c) = a^(b-c)
a^-b = 1/a^b
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Comment on notation
When writing a fraction in plain text, any denominator that includes an arithmetic operation must be enclosed in parentheses. Your given expression is properly written as ...
-3x^5y/(6xy^8)
Without the parentheses, the product xy^8 is in the numerator. This is demanded by the order of operations, which requires you evaluate your expression as (-3x^5y^7/6)·xy^8