GMAT prep

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GMAT prep

by rajt » Fri May 18, 2007 3:16 pm
This should be easy but is driving me nuts.
if 0<x<y what is the value of (x+y)^2/(x-y)^2

1. x^2 +y^2 = 3xy
2. xy =3

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by bww » Fri May 18, 2007 3:44 pm
Is answer B?

1) not sufficient

2) plugging in xy=3 into the question...

(x^2+2(9)+y^2)/(x^2-2(9)+y^2)=
(x^2+y^2)/(x^2+y^2)=
=1

Am I missing something? Can anything be done with the information given in 1)?

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Re: GMAT prep

by jayhawk2001 » Fri May 18, 2007 4:00 pm
rajt wrote:This should be easy but is driving me nuts.
if 0<x<y what is the value of (x+y)^2/(x-y)^2

1. x^2 +y^2 = 3xy
2. xy =3
Is it A ?

1 - sufficient.

(x^2 + y^2 + 2xy) / (x^2 + y^2 - 2xy)
= 5xy / xy
= 5

2 - insufficient. Cannot simplify beyond (x^2 + y^2 + 6) / (x^2 + y^2 - 6)

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by Cybermusings » Sat May 19, 2007 1:18 am
My answer is same as Jay....it should be A

Statement A:
(x+y)^2 =x^2+y^2+2xy
(x-y)^2=x^2+y^2-2xy
So 3xy+2xy / 3xy-2xy = 5xy/xy = 5

Statement B: Insufficient

Hence A

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by bww » Sat May 19, 2007 2:10 am
oh wow. that's pretty clear--thanks!