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Source: — Data Sufficiency |
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by anshumishra » Sun Jan 09, 2011 12:37 pm
diebeatsthegmat wrote:Is (x^2 + y^2) a perfect square?

(1) x is even, y is odd
(2) x and y are odd

[spoiler] the answer is B and i dont understand, for me it should be E because a or y can be squrt3 +1^6=4=2^2[/spoiler]
sqrt3 is not odd (or even), it is an irrational number.
Try with any odd number (3,5,9,etc..), then you can see whether B is sufficient.
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by clock60 » Sun Jan 09, 2011 12:52 pm
hi all
for st 2
if x,y both are odd then x^2+y^2=even ( odd+odd=even)
and the square of even integer must be divisible by 4. (2k)^2=4k^2, if x, y both odd then
x=2k+1, y=2a+1
(2k+1)^2+(2a+1)^2=4k^2+4k+4a^2+4a+2
here sum is divisible by 2

(1) clearly many possible pairs
1^2+2^2=5 not perfect square
5^2+12^2=13^2 perfect square
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by Tani » Sun Jan 09, 2011 3:10 pm
For any data sufficiency problem on an actual GMAT, BOTH clues must be true. Therefore, they cannot contradict each other. In the example you have given, the first and second clues cannot both be true.
Tani Wolff
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by bblast » Mon Jan 10, 2011 10:51 am
anshumishra wrote:
diebeatsthegmat wrote:Is (x^2 + y^2) a perfect square?

(1) x is even, y is odd
(2) x and y are odd

[spoiler] the answer is B and i dont understand, for me it should be E because a or y can be squrt3 +1^6=4=2^2[/spoiler]
sqrt3 is not odd (or even), it is an irrational number.
Try with any odd number (3,5,9,etc..), then you can see whether B is sufficient.


B is sufficient as in it answers the question as a NO
correct Anshu ?

agree with Tani, question is ambiguous.
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by anshumishra » Mon Jan 10, 2011 10:54 am
bblast wrote:
anshumishra wrote:
diebeatsthegmat wrote:Is (x^2 + y^2) a perfect square?

(1) x is even, y is odd
(2) x and y are odd

[spoiler] the answer is B and i dont understand, for me it should be E because a or y can be squrt3 +1^6=4=2^2[/spoiler]
sqrt3 is not odd (or even), it is an irrational number.
Try with any odd number (3,5,9,etc..), then you can see whether B is sufficient.


B is sufficient as in it answers the question as a NO
correct Anshu ?

agree with Tani, question is ambiguous.
Yes, B is Sufficient.
Thanks
Anshu

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