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by roybudhaditya » Fri Oct 05, 2007 5:29 am
If x is a postive integer,which of the following could be the correct ordering of 1/x,,2x,,x square......

1:- x square<2x<1/x
2:- x square<1/x<2x
3:-2x< x square<1/x..

A- NONE
B--3 ONLY
C--1 ONLY
D--1 & 2 ONLY.
E--1,2 & 3 ONLY.

Hii,,can anyone plss explain this??
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by ldoolitt » Fri Oct 05, 2007 7:19 am
Anonymous wrote:If X is a positive integer, then x and x^2 should always be greater than or equal to 1 and 2x is always greater than or equal to 2. Having said that, 1/x is less than or equal to 1 because 1/1 is 1 and as x gets larger, 1/x becomes smaller.

Having said that, any answer choice that places 2x to the left of 1/x can be eliminated because the minimum value for 2x is 2, and the maximum value for 1/x is 1, so 2x must always be greater than 1/x. You can eliminate 1 & 3.

Now, with #2: can x^2 be smaller than 1/x? x^2 can be equal to 1/x, but it can never be smaller. Again, when x=1 both x^2 and 1/x also equal to 1. However, as x gets larger, the value of x^2 gets larger while the value of 1/x gets smaller. So 2 is also out because it says that x^2 could be larger than 1/x which is not true.
The problem definition is funny. Is it supposed to be (-x)^2 or -(x^2) as the term in the problem? If it is -(x^2) which is how I read it, the bold part in the answer above is wrong and 2 is correct. Otherwise the above solution is correct.

Would the answer then be (a)?
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by yass » Fri Oct 05, 2007 10:21 am
I think the answer should be A (none)

x>0 ==> 1/x , 2x, x^2

x = 1 ==> 1 , 2 , 1 (1/x=x^2 < 2x)

x = 2 ==> 1/2, 4, 4 (x^2= 2x > 1/x)

x = 3 ==> 1/3, 6 , 9 (x^2 > 2x > 1/x)

So depending on the value of x, we get different results.
If x>2, then we could have had one single result.
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by roybudhaditya » Fri Oct 05, 2007 10:32 am
Hello guys,,,
I have read alll the answers & I am delighted to say that you all have done exctly what I did in the exam..I ticked A..But then the answer arrived,,it showed that the OA is D ,,that means 1 & 11 must be correct....I was totally abak that my actual gmat is on Tuesday & how could I do this type of mistake.
bUT I checked througly & I was unable to get the right answer.

How could 1 & 111 be right..I dont know..any more approach????
Regards.
Aditya..
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by ldoolitt » Mon Oct 08, 2007 7:00 am
Are you sure you copied down the problem correctly? Those greater than signs are not greater than or equal to? And is it negative x squared or (negative x) squared?
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