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If x2 + y2 = 1, is x + y = 1? (1) xy = 0 (2) y = 0

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vivektripathi
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 Q50  V31
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If x2 + y2 = 1, is x + y = 1? (1) xy = 0 (2) y = 0 [#permalink] New post   01 Dec 2008, 08:50
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If x2 + y2 = 1, is x + y = 1?
(1) xy = 0
(2) y = 0



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Re: If x2 + y2 = 1, is x + y = 1? (1) xy = 0 (2) y = 0 [#permalink] New post   01 Dec 2008, 09:40
IMO E

Even combined, x can be either 1 or -1, Insuff
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HG
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Re: If x2 + y2 = 1, is x + y = 1? (1) xy = 0 (2) y = 0 [#permalink] New post   01 Dec 2008, 16:07
IMO C

Here is why

x+y = 1
or
(x+y)^2 = 1

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

1+2xy = 1 ( x^2+y^2 = 1 - given in Q)

or the question is asking is xy =0?

1 - Suff
2- Suff
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selvae
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Re: If x2 + y2 = 1, is x + y = 1? (1) xy = 0 (2) y = 0 [#permalink] New post   01 Dec 2008, 20:04
IMO E

x2 + y2 = 1 deriving from Q (x+y)^2 = 1+2xy

1) xy = 0; so x+y = +/- 1
2) y=0; x2 = 1; x+y = +/- 1
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Re: If x2 + y2 = 1, is x + y = 1? (1) xy = 0 (2) y = 0 [#permalink] New post   02 Dec 2008, 05:05
HG wrote:
IMO C

Here is why

x+y = 1
or
(x+y)^2 = 1

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

1+2xy = 1 ( x^2+y^2 = 1 - given in Q)

or the question is asking is xy =0?

1 - Suff
2- Suff


Value of X could be -1 or +1 hence E OA isE



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Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
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Thank you for understanding, and happy exploring!
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gmatclubot
Re: If x2 + y2 = 1, is x + y = 1? (1) xy = 0 (2) y = 0 [#permalink]
02 Dec 2008, 05:05
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