Modulus problem

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Source: — Data Sufficiency |

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by macattack » Mon Aug 12, 2013 10:17 pm
Rephrase the question: Is -1<x<1?

Case 1:
x^4-1>0
x^4>1
For x to an even power be greater than 1---> x<-1 or x>1. If x is between -1 and 1 x to an even power has to be between 0 and 1.
Sufficient

Case 2:
1/(|x| - 1)>0 (1 is a positive constant)---> |x|-1>0
|x|>1---> x<-1 or x>1
Sufficient

OA is D

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by ganeshrkamath » Tue Aug 13, 2013 12:50 am
Mission2012 wrote:Is |x| < 1

(i) x^4 - 1 > 0
(ii)1/(|x| - 1) > 0
Statement 1: x^4 - 1 > 0
x^4 > 1
x > 1
Sufficient

Statement 2: 1/(|x| - 1) > 0
|x| - 1 > 0
|x| > 1
Sufficient

Choose D.
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