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# The function f is defined as f(x,y) = xy for positive numbers x and y.

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Senior Manager
Joined: 18 Feb 2019
Posts: 385
Location: India
GMAT 1: 460 Q42 V13
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The function f is defined as f(x,y) = xy for positive numbers x and y.  [#permalink]

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29 Mar 2019, 12:26
00:00

Difficulty:

45% (medium)

Question Stats:

20% (00:08) correct 80% (01:51) wrong based on 5 sessions

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The function f is defined as f(x,y) = xy for positive numbers x and y. If f(x,1/x)=f(x,y), which of the following must be true?

A. f(x,x)=f(y,y)
B. f(x,1/x)=f(x,1/y)
C. f(x+y,1/x)=f(x+y,1/y)
D. f(x^2,y^2)=f(y(x+1),1/(y+1))
E. f(x,1y)=1
Math Expert
Joined: 02 Sep 2009
Posts: 55274
Re: The function f is defined as f(x,y) = xy for positive numbers x and y.  [#permalink]

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30 Mar 2019, 00:32
kiran120680 wrote:
The function f is defined as f(x,y) = xy for positive numbers x and y. If f(x,1/x)=f(x,y), which of the following must be true?

A. f(x,x)=f(y,y)
B. f(x,1/x)=f(x,1/y)
C. f(x+y,1/x)=f(x+y,1/y)
D. f(x^2,y^2)=f(y(x+1),1/(y+1))
E. f(x,1y)=1

_________________
Re: The function f is defined as f(x,y) = xy for positive numbers x and y.   [#permalink] 30 Mar 2019, 00:32
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