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If x and y are positive integers, each of the following
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29 Sep 2012, 11:41
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If x and y are positive integers, each of the following could be the greatest common divisor of 30x and 15y EXCEPT A. 30x. B. 15y. C. 15(x + y). D. 15(x  y). E. 15,000.
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Re: If x and y are positive integers, each of the following
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29 Sep 2012, 12:29
smartass666 wrote: If x and y are positive integers, each of the following could be the greatest common divisor of 30x and 15y EXCEPT
30x. 15y. 15(x + y). 15(x  y). 15,000. The greatest common divisor must be smaller than each number. \(15(x+y)>15y\), so for sure, \(15(x+y)\) cannot be a divisor of \(15y.\) Answer C.
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Re: If x and y are positive integers, each of the following
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01 Oct 2012, 05:23



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Re: If x and y are positive integers, each of the following
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29 Nov 2013, 12:22
Wait a minute, picking numbers: If x= 1 and y =1 , both positive integers, why this could not be the base case for C? smartass666 wrote: If x and y are positive integers, each of the following could be the greatest common divisor of 30x and 15y EXCEPT
A. 30x. B. 15y. C. 15(x + y). D. 15(x  y). E. 15,000.



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Re: If x and y are positive integers, each of the following
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29 Nov 2013, 12:25
nechets wrote: Wait a minute, picking numbers: If x= 1 and y =1 , both positive integers, why this could not be the base case for C? smartass666 wrote: If x and y are positive integers, each of the following could be the greatest common divisor of 30x and 15y EXCEPT
A. 30x. B. 15y. C. 15(x + y). D. 15(x  y). E. 15,000. If x=1 and y=1, then 30x=30 and 15y=15. The GCD of 30 and 15 is 15, while (C) gives 15(x+y)=30. Hope it's clear.
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Re: If x and y are positive integers, each of the following
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29 Nov 2013, 12:31
Fantastic Bunuel, great catch. Is it the case that x/(x+y) or y/(x+y) will never be integer? Is this the right way to elimate C algebraically? Or how would you do so? Bunuel wrote: nechets wrote: Wait a minute, picking numbers: If x= 1 and y =1 , both positive integers, why this could not be the base case for C? smartass666 wrote: If x and y are positive integers, each of the following could be the greatest common divisor of 30x and 15y EXCEPT
A. 30x. B. 15y. C. 15(x + y). D. 15(x  y). E. 15,000. If x=1 and y=1, then 30x=30 and 15y=15. The GCD of 30 and 15 is 15, while (C) gives 15(x+y)=30. Hope it's clear.



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Re: If x and y are positive integers, each of the following
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29 Nov 2013, 12:41
nechets wrote: Fantastic Bunuel, great catch. Is it the case that x/(x+y) or y/(x+y) will never be integer? Is this the right way to elimate C algebraically? Or how would you do so? Bunuel wrote: nechets wrote: Wait a minute, picking numbers:
If x= 1 and y =1 , both positive integers, why this could not be the base case for C?
If x and y are positive integers, each of the following could be the greatest common divisor of 30x and 15y EXCEPT
A. 30x. B. 15y. C. 15(x + y). D. 15(x  y). E. 15,000. If x=1 and y=1, then 30x=30 and 15y=15. The GCD of 30 and 15 is 15, while (C) gives 15(x+y)=30. Hope it's clear. Both x and y are positive integers, thus \(\frac{15y}{15(x+y)}=\frac{y}{x+y}\neq{integer}\) because the denominator is greater than the numerator. Thus 15(x+y) cannot be a divisor of 15y. Check similar questions to practice: whichofthefollowingcannotbethegreatestcommondivisor108865.htmlifxandyarepositiveintegerswhichofthefollowing74924.htmlHope this helps.
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Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
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Re: If x and y are positive integers, each of the following
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Re: If x and y are positive integers, each of the following
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