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If x and y are both integers greater than 1, is x a multiple
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04 May 2008, 19:26
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64% (01:32) correct 36% (01:53) wrong based on 278 sessions
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If x and y are both integers greater than 1, is x a multiple of y? (1) 3y^2 + 7y = x (2) x^2 x is a multiple of y
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Re: DS: x multiple of y?
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04 May 2008, 20:35
chineseburned wrote: If x and y are both integers greater than 1, is x a multiple of y?
(1) 3y^2 + 7y = x (2) x^2 x is a multiple of y Hi, it is long time to see you! 1 suff. no discustion 2. x(x1) is multiple of y. So x may or may not is multiple of y. a. x=5, y = 2 5*6 is multiple of 2, but x=5 is not multiple of 2 b. x=6 6*7 is multiple of 2, and x=6 is multiple of 2
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Re: DS: x multiple of y?
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04 May 2008, 20:55
chineseburned wrote: If x and y are both integers greater than 1, is x a multiple of y?
(1) 3y^2 + 7y = x (2) x^2 x is a multiple of y A. Given: x > 1 y > 1 n, x, y = integer Asking: Is x = ny? (1) x = y*(3y + 7) Because y is integer, (3y + 7) must be integer; therefore, x must equal integer * y SUFFICIENT (2) x^2  x = ny Plug in numbers to satisfy above condition... Say x=3, n=1, then y=6. In this case, x is not a multiple of y. Say x=6, n=15, then y=2. In this case, x is a multiple of y. The solution actually depends on what n is, and the only condition we have is n is integer. Therefore, it is INSUFFICIENT



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Re: DS: x multiple of y?
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04 May 2008, 21:29
chineseburned wrote: If x and y are both integers greater than 1, is x a multiple of y?
(1) 3y^2 + 7y = x (2) x^2 x is a multiple of y (1) 3y^2 + 7y = x y (3y + 7) = x so x must be a multiple, (3y+7) times, of y. suff... (2) x^2 x is a multiple of y x^2  x = yk where k is an integer. x (x1) = yk from this we do not know whether x  1 or x is equal to k. so nsf.... A.
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Re: DS: x multiple of y?
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24 Jun 2008, 18:02
GMAT TIGER wrote: (2) x^2 x is a multiple of y x^2  x = yk where k is an integer. x (x1) = yk from this we do not know whether x  1 or x is equal to k. so nsf....
What is the reasoning behind multiplying y by another variable in Statement 2 (in this case k)?



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Re: DS: x multiple of y?
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24 Jun 2008, 23:26
AlinderPatel wrote: GMAT TIGER wrote: (2) x^2 x is a multiple of y x^2  x = yk where k is an integer. x (x1) = yk from this we do not know whether x  1 or x is equal to k. so nsf....
What is the reasoning behind multiplying y by another variable in Statement 2 (in this case k)? 2)x^2 x is a multiple of y let K be the multiple. then x^2x = K . y Hope this helps



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Re: DS: x multiple of y?
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10 Jun 2010, 07:41
so if we have
y^2y = X
Then we could say with certitude that X is a multiple of Y?



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Re: DS: x multiple of y?
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10 Jun 2010, 07:54
Yes. If it was given that y^2y = x, then x is certainly a multiple of y.
y^2y = x y(y1) = x y*k = x



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Re: DS: x multiple of y?
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17 Jul 2010, 07:52
So from x(x1)=yk, can we not derive: x=y*k/(x1)=yk? In which case the answer is C, not A.
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Re: DS: x multiple of y?
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17 Jul 2010, 08:12
dauntingmcgee wrote: So from x(x1)=yk, can we not derive:
x=y*k/(x1)=yk?
In which case the answer is C, not A. We don't know whether \(\frac{k}{x1}\) is an integer, hence we can not write \(x=yn\) (where n is an integer) from \(x(x1)=yk\). If x and y are integers great than 1, is x a multiple of y?Is \(x=ny\), where \(n=integer\geq{1}\)? (1) \(3y^2+7y=x\) > \(y(3y+7)=x\) > as \(3y+7=integer\), then \(y*integer=x\) > \(x\) is a multiple of \(y\). Sufficient. (2) \(x^2x\) is a multiple of \(y\) > \(x^2x=my\) > \(x(x1)=my\) > \(x\) can be multiple of \(y\) (\(x=2\) and \(y=2\)) OR \(x1\) 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. Answer: A. Hope it helps.
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Re: DS: x multiple of y?
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17 Jul 2010, 10:46
Yes, that is great. Thank you. Guess I'm a little rustier than I thought.
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Re: If x and y are both integers greater than 1, is x a multiple
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19 Aug 2018, 00:29
could someone please explain me the option 2 by plugging numbers. I have not understood the above solutions. Thank you.
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Re: If x and y are both integers greater than 1, is x a multiple
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19 Aug 2018, 09:12
SonGoku wrote: could someone please explain me the option 2 by plugging numbers. I have not understood the above solutions. Thank you. (2) \(x^2−x\) is a multiple of y Number plugging approach: Let \(y=2\) If \(x=3\) > \(x^2−x\) = \(3^23 = 6\) > \(x^2−x\) is a multiple of y BUT x is not a multiple of y > NO If \(x=4\) > \(x^2−x\) = \(4^24 = 12\) > \(x^2−x\) is a multiple of y and x is a multiple of y > YES > Insufficient. Hope it's clear.
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Re: If x and y are both integers greater than 1, is x a multiple
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19 Aug 2018, 09:12






