Discussion
If x and y are positive integers, is 
an integer?
*This question is included in Data Sufficiency Free Lesson Set, question #4
an integer?
(1) y − x = 0
(2) xy = 1 for some positive integer y.
| (A) | if statement (1) ALONE is sufficient to answer the question but statement (2) alone is not sufficient; |
| (B) | ... |
| (C) | ... |
| (D) | ... |
| (E) | ... |
| (F) | ... |
The solution is
Posted: 08/13/2012 22:21
It's not an integer anyway,so I think E is the correct choice
Posted: 08/17/2012 17:19
Alice, from 1, we know x=y, hence √(2xy) = √(2x^2) = x√2. We conclude √(2xy) is not an integer.
From 2, we know xy=1, so √(2xy)=√2, hence we conclude √(2xy) is also not an integer.
We can answer the question independently with each statement, hence D is the correct choice.
From 2, we know xy=1, so √(2xy)=√2, hence we conclude √(2xy) is also not an integer.
We can answer the question independently with each statement, hence D is the correct choice.
Posted: 08/22/2012 05:52
But in II it says for "some positive y" so we can not apply this since some y values Will violate
Therefore A must be the correct choice
Therefore A must be the correct choice
Posted: 06/06/2013 23:28
For some positive INTEGER y, xy=1. Then y cannot by anything but 1, and x=1. xy=1 is a constraint that cannot be violated. Even though it says some positive integer y, it can only be 1.
Posted: 08/22/2012 11:01
Ersen, can you give an example?
Posted: 06/05/2013 06:34
For other positive integer y,it can be true that xy don not equal to 1,so ii may be wrong
Posted: 06/05/2013 06:35
Say,xy=2,the result may be an integer.we can not say ii is correct for sure.
Posted: 06/06/2013 23:30
For some positive INTEGER y, xy=1. Then y cannot by anything but 1, and x=1. xy=1 is a constraint that cannot be violated. Even though it says some positive integer y, it can only be 1. Why do you say xy=2, when the data piece in (ii) clearly states in (ii) xy=1?