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# If x and y are positive integers, which of the following

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CEO
Joined: 21 Jan 2007
Posts: 2739
Location: New York City
If x and y are positive integers, which of the following [#permalink]

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11 Feb 2008, 12:12
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

If x and y are positive integers, which of the following CANNOT be the greatest common divisor of 35x and 20y?

5
5(x – y)
20x
20y
35x
_________________

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CEO
Joined: 29 Mar 2007
Posts: 2560

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11 Feb 2008, 12:53
bmwhype2 wrote:
If x and y are positive integers, which of the following CANNOT be the greatest common divisor of 35x and 20y?

5
5(x – y)
20x
20y
35x

I think its C

A: obvs can be.
B: x=2 and y=1 5x-5y=5 then and it can be a common a GCF
D: what if 35x=20y
E: what if 35x=20y

Now obvs 20x cannot equal 35x. This is where I gathered that the answer is C. I am not certain here.
Intern
Joined: 02 Feb 2008
Posts: 4

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11 Feb 2008, 13:58
i think it's b.
if x and y are 1, 5*(1-1) is not the gcd of 20 and 35
el doktor!
Director
Joined: 01 Jan 2008
Posts: 622

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11 Feb 2008, 14:24
bmwhype2 wrote:
If x and y are positive integers, which of the following CANNOT be the greatest common divisor of 35x and 20y?

5
5(x – y)
20x
20y
35x

it's C. 20x is not a divisor of 35x because 20 is not a divisor of 35.
Director
Joined: 01 May 2007
Posts: 793

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11 Feb 2008, 15:47
I agree C. for same reason. I
Re: MGMAT - GCF   [#permalink] 11 Feb 2008, 15:47
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