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02 Jan 2011, 14:08
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A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
15%
(low)
Question Stats:
77% (00:40) correct
23%
(00:47)
wrong
based on 339
sessions
History
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Not Attempted Yet
02 Jan 2011, 14:22
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SergeNew
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.
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.
Answer: A.
Hope it's clear.
12 Nov 2017, 08:40
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SergeNew
What is the value of x^2-y^2?
(1) x+y=0
(2) x-y=2 .
(1) x+y=0
(2) x-y=2 .
We need to determine the value of x^2 - y^2. Notice that x^2 - y^2 = (x + y)(x - y).
Statement One Alone:
x + y = 0
Since x + y = 0, regardless of the value of x - y, we have x^2 - y^2 = (x + y)(x - y) = (0)(x - y) = 0. Statement one alone is sufficient to answer the question.
Statement Two Alone:
x - y = 2
We do not have enough information to determine a definitive value for x^2 - y^2. For example, if x = 4 and y = 2, then x^2 - y^2 = 16 - 4 = 12; however, if x = 3 and y = 1, then x^2 - y^2 = 9 - 1 = 8. Statement two alone is not sufficient to answer the question.
Answer: A
