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* If X & Y are positive integers such that x=8y+12

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a123
 Post subject: * If X & Y are positive integers such that x=8y+12
 Post Posted: Sun Jul 17, 2011 1:38 pm 
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Course Students


Posts: 4
If X & Y are positive integers such that x=8y+12,
What's the greatest common divisor of X & Y

1. X = 12u (u = integer)

2. Y = 12u (u = integer)

Answer is B.

I'm confused as both (1) and (2) give you 3,2,2 as prime factors for the GCD. Why is (2) sufficient but (1) not?

Is it because Y is already divisible by 8 (shown by 8Y)?

Thanks
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RonPurewal
 Post subject: Re: If X & Y are positive integers such that x=8y+12
 Post Posted: Wed Jul 20, 2011 5:23 am 
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ManhattanGMAT Staff


Posts: 7146
please search the forum before you post; there are lots and lots and lots of threads on this problem.

here's the longest:
in-x-and-y-are-positive-integers-such-that-x-8y-12-t902.html

if you have any further questions after reading that thread, please post them there, not here.
thanks.

this thread is now locked, and will be deleted shortly.
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