Practice DS, Section 3, Question 15

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Practice DS, Section 3, Question 15

by airan » Sun Jun 01, 2008 1:19 am
If x!=0, is |x| < 1

1. x^2 < 1
2. |x| < 1/x.


Pls advise a strategy where modules questions have values equated to 1. i.e. not in the range.
Thanks
Airan

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by amitansu » Sun Jun 01, 2008 4:13 am
If the q says: x is not equal to 0
is mod(x)<1 ?

1)x^2<1
2)mod(x)<1/x



From 1 : x^2<1> +0r- (x)<1 which is mod(x)<1 here x being a factor.So sufficient.

From 2: mod(x)<1>+or-(x)<1/x (x is a factor here) but with -x being a factor would contradict the value.For example let x =1/2
so 1/2<1>1/2<2; but is -1/2 < 1/-(1/2) no.

However we are asked about whether mod(x)<1 ?
and from above we knew, yes definitely.So suficient.

Ans D.

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by jasonc » Sun Jun 01, 2008 4:17 am
Given:If x!=0, is |x| < 1
implied questoin:
is SQRT(x^2)<1> x^2<1

1. x^2 < 1.
suff

2. |x| < 1/x.
don't know if x is poitive or negative. insuff

answer should be A
I beat the GMAT! 760 (Q49/V44)

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by amitansu » Sun Jun 01, 2008 8:24 am
A little confusion !

About stem 2 : it says : mod(x)<1>+or-x<1>x^2<1 so sufficient (this is my understanding)

Please clarify.

Amit