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Y an iInteger?

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Y an iInteger?

by crackgmat007 » Wed May 06, 2009 9:46 am
Q: If x + y is an integer, is y an integer?
(1) x – y is an integer.
(2) x + 2y is an integer.

Can I plug-in values to answer such type of questions? Pls help me solve this problem?

OA – B
Last edited by crackgmat007 on Thu May 07, 2009 4:30 pm, edited 1 time in total.
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by DanaJ » Wed May 06, 2009 10:42 am
1. eliminate this one with a simple numeric example:
x = 3.5
y = 1.5
While x + y = 5 - integer and x - y = 2 - integer, y is not an integer.

But take:
x = 2
y = 1
This time, x + y, x - y and y are all integers.

2. x + 2y is an integer helps you since you know that x + y is also an integer. x + 2y = (x + y) + y and since what you have in the parentheses is an integer, y must also be an integer.
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by jitendragneogi » Thu May 07, 2009 3:28 pm
For St 2 if I take

3 + 2 * 2.5 = x + 2y = 8 = Int.

But x + y = 3 + 2.5 = 5.5 = Not an Integer.

Won't C be OA here?
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by cramya » Thu May 07, 2009 4:28 pm
For St 2 if I take

3 + 2 * 2.5 = x + 2y = 8 = Int.

But x + y = 3 + 2.5 = 5.5 = Not an Integer.

Won't C be OA here?
In the case above x+y will not be an integer as given in the problem

3+2.5 -> not an integer

Hope this helps.
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