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Is Ix-yI >IxI - IyI

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davo45
 Post subject: Is Ix-yI >IxI - IyI
 Post Posted: Fri Jul 08, 2011 1:57 pm 
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Students


Posts: 1
G'day all

This following qn appeare in GMAT Prep 1. Is my logic correct?

Is Ix-yI > IxI - IyI ?

(1) y<x
(2) xy <0

Ans is B

say x=3 y=-2

|3--2|> |3| - |-2| 5>1


2: Now for this use x=3, y=-2 and x=-3 and y=2.

We get 5>1 for both.
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varun_783
 Post subject: Re: Is Ix-yI >IxI - IyI
 Post Posted: Fri Jul 08, 2011 2:25 pm 
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Course Students


Posts: 263
Hi,

My understanding is that you are OK with the answer and just want clarification on the method that you have used.

Your statement 2 seems fine. The key is here is that x and y have opposite signs.

Statement 1, you have only used one set of numbers. I would use another just to make sure that I can rule it out.

e.g: x = 3 and y = 2

|3 - 2| > |3| - |2|
=> 1 > 1 (No)

Using this and your combination, we can safely rule out statement 1.

Hope this helps

Regards

Sunil
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RonPurewal
 Post subject: Re: Is Ix-yI >IxI - IyI
 Post Posted: Thu Jul 14, 2011 6:40 pm 
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ManhattanGMAT Staff


Posts: 7146
that's basically the idea -- this is definitely a problem on which plugging numbers is superior to the existing alternatives.

here's my take on the same problem, from earlier:
post50428.html#p50428
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