Which expression is equivalent to [tex]\left(\frac{x^{-4} y}{x^{-9} y^5}\right)^{-2}[/tex]? Assume [tex]x \neq 0, y \neq 0[/tex].

A. [tex]\frac{y^8}{x^{10}}[/tex]

B. [tex]\frac{x^5}{y^7}[/tex]

C. [tex]\frac{x^5}{y^4}[/tex]

D. [tex]\frac{x}{y^7}[/tex]



Answer :

To solve the expression [tex]\(\left(\frac{x^{-4} y}{x^{-9} y^5}\right)^{-2}\)[/tex], we will first simplify the fraction inside the parentheses and then apply the exponent [tex]\(-2\)[/tex] to the result.

1. Start with the expression inside the parentheses:
[tex]\[ \frac{x^{-4} y}{x^{-9} y^5} \][/tex]

2. Simplify each part of the fraction:
- Simplify the [tex]\(x\)[/tex] terms:
[tex]\[ \frac{x^{-4}}{x^{-9}} = x^{-4 - (-9)} = x^{-4 + 9} = x^5 \][/tex]
- Simplify the [tex]\(y\)[/tex] terms:
[tex]\[ \frac{y}{y^5} = y^{1-5} = y^{-4} \][/tex]

3. Combine the simplified parts:
[tex]\[ \frac{x^{-4} y}{x^{-9} y^5} = x^5 y^{-4} \][/tex]

4. Now, apply the exponent [tex]\(-2\)[/tex] to the simplified expression:
[tex]\[ \left(x^5 y^{-4}\right)^{-2} \][/tex]

5. Distribute the exponent [tex]\(-2\)[/tex] to both [tex]\(x^5\)[/tex] and [tex]\(y^{-4}\)[/tex]:
- For [tex]\(x^5\)[/tex]:
[tex]\[ \left(x^5\right)^{-2} = x^{5 \cdot -2} = x^{-10} \][/tex]
- For [tex]\(y^{-4}\)[/tex]:
[tex]\[ \left(y^{-4}\right)^{-2} = y^{-4 \cdot -2} = y^8 \][/tex]

6. Combine the results:
[tex]\[ x^{-10} y^8 = \frac{y^8}{x^{10}} \][/tex]

Therefore, the expression equivalent to [tex]\(\left(\frac{x^{-4} y}{x^{-9} y^5}\right)^{-2}\)[/tex] is [tex]\(\frac{y^8}{x^{10}}\)[/tex].

The correct answer is:
[tex]\[ \boxed{\frac{y^8}{x^{10}}} \][/tex]