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# DS problem GMAT Prep on Numbers

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Kudos [?]: 3 [0], given: 15

DS problem GMAT Prep on Numbers [#permalink]  13 Aug 2010, 03:07
00:00

Question Stats:

50% (00:00) correct 50% (02:47) wrong based on 0 sessions
Please answer. I had to guess, coz I couldn't figure out the answer and ended up in a bad guess!
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Kudos [?]: 9613 [3] , given: 829

Re: DS problem GMAT Prep on Numbers [#permalink]  13 Aug 2010, 03:21
3
KUDOS
If x and y are integers great than 1, is x a multiple of y?

Question: is x=ny?

(1) 3y^2+7y=x --> y(3y+7)=x --> as 3y+7 is an integer, so x is a multiple of y. Sufficient.

(2) x^2-x is a multiple of y --> x^2-x=my --> x(x-1)=my --> x can be multiple of y (x=2 and y=2) OR x-1 can be multiple of y (x=3 and y=2) or their product can be multiple of y (x=3 and y=6). Not sufficient.

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Re: DS problem GMAT Prep on Numbers [#permalink]  14 Aug 2010, 09:03
I also fell for D. But thanks to Bunel's explanation, i spotted the detail.
Re: DS problem GMAT Prep on Numbers   [#permalink] 14 Aug 2010, 09:03
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