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# What is the value of x^2-y^2? (1) x+y=0 (2) x-y=2

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What is the value of x^2-y^2? (1) x+y=0 (2) x-y=2 [#permalink]

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02 Jan 2011, 14:08
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What is the value of x^2-y^2?

(1) x+y=0
(2) x-y=2

Hello Folks,

This question is from the review published in 2010. Could anyone please explain to me why the correct answer is A instead of D?

Thank you so much and Happy new decade to everyone.

Serge.
[Reveal] Spoiler: OA
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02 Jan 2011, 14:22
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SergeNew wrote:
Hello Folks,

This question is from the review published in 2010. Could anyone please explain to me why the correct answer is A instead of D?

What is the value of x^2-y^2?

1) x+y=0
2) x-y=2

A) Statement (1) Alone is Sufficient but Statement (2) Alone is not sufficient.
D) Each statement Alone is sufficient.

Thank you so much and Happy new decade to everyone.

Serge.

Welcome to Gmat Club Serge!

What is the value of x^2-y^2?

Question: $$x^2-y^2=(x-y)*(x+y)=?$$

(1) x+y=0 --> as one of the multiples is zero then $$(x-y)*(x+y)$$ must equal to zero. Sufficient.

(2) x-y=2 --> we can not get a single numerical value of x^2-y^2 from this statement. For example: if $$x=2$$ and $$y=0$$ then the answer will be 4 but if $$x=1$$ and $$y=-1$$ then the answer will be 0. Not sufficient.

Hope it's clear.
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Re: What is the value of x^2-y^2? (1) x+y=0 (2) x-y=2 [#permalink]

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24 Nov 2013, 08:47
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24 Apr 2016, 05:31
Hello from the GMAT Club BumpBot!

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Re: What is the value of x^2-y^2? (1) x+y=0 (2) x-y=2   [#permalink] 24 Apr 2016, 05:31
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