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# If xy = 1 and x is not equal to y, then what is the value of

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Re: If xy = 1 and x is not equal to y, then what is the value of [#permalink]
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Showmeyaa wrote:
Hey BrentGMATPrepNow,

Not that it changes the answer but I'm sure you meant:

Simplify: $$=7 ^{(\frac{-1}{xy})}$$

Substitute $$1$$ for $$xy$$ to get: $$=7 ^{(\frac{-1}{1})} = 7^{-1}=\frac{1}{7}$$

Good catch, thanks!
I've edited my response.

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If xy = 1 and x is not equal to y, then what is the value of [#permalink]
Given that xy=1 and x is not equal to y
So y=1/x
Substitute y=1/x in given expression
$$(7 ^{(\frac{1}{x-y})})^{(\frac{1}{x}- \frac{1}{y})}$$
We get (7)^-1/xy ; xy=1 ; 1/7
Option B

Bunuel wrote:
If xy = 1 and x is not equal to y, then what is the value of $$(7 ^{(\frac{1}{x-y})})^{(\frac{1}{x}- \frac{1}{y})}$$?

A. $$\frac{1}{49}$$

B. $$\frac{1}{7}$$

C. 1

D. 7

E. 49

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If xy = 1 and x is not equal to y, then what is the value of [#permalink]
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