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GMAT Prep?? (Variables)

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Re: GMAT Prep?? (Variables)

by bha » Thu Aug 07, 2008 9:00 am
dferm wrote:If 0<x<y, what is the value of (x+y)^2/(x-y)^2 ?

(1) x^2+y^2 = 3xy
(2) xy = 3

Can someone please Help....

I picked C as my answer.....
i think correct answer is A.
(x+y)^2/(x-y)^2
(X^2+Y^2+2XY)/(X^2+Y^2-2XY)...eqn1
Using stmt 1,
Eqn1 becomes (3xy+2xy)/(3xy-2xy)= 5..sufficient
using stmt2
Eqn1 becomes (X^2+Y^2+6)/(X^2+Y^2-6) not sufficient
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by dferm » Thu Aug 07, 2008 10:37 am
I think that your are wrong.... where are you getting 5 from....it was never mentioned....
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by bha » Thu Aug 07, 2008 10:44 am
dferm wrote:I think that your are wrong.... where are you getting 5 from....it was never mentioned....
5 is answer we get by substituting stmt1 in equation to be solved...
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by Stuart@KaplanGMAT » Thu Aug 07, 2008 10:50 am
dferm wrote:I think that your are wrong.... where are you getting 5 from....it was never mentioned....
Using stmt 1,
Eqn1 becomes (3xy+2xy)/(3xy-2xy)= 5..sufficient
Going through the steps:

(3xy+2xy)/(3xy-2xy) = 5xy/xy = 5
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by dferm » Thu Aug 07, 2008 10:50 am
I don't understand your logic.... we still have xy as our unknown.. i could see how both are sufficient but A alone won't do it.....
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by dferm » Thu Aug 07, 2008 10:52 am
Thank you Stuart....I now understand why A is sufficient....
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by dferm » Thu Aug 07, 2008 10:53 am
Bha... thank you as well.....I just didn't understand the leap you made.... but I get it now....
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