modular arithmetic

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modular arithmetic

by ildude02 » Wed Jun 25, 2008 8:31 am
Is |x| < 1?

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

Can someone explain how you breakdown statement 2 considering x can be < or < 0. Appreciate it

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by atlantic » Wed Jun 25, 2008 10:13 am
Hi Ildude02,

(1) obviously SUFF

(2) x < 1/x or -x < 1/x

The first equation says that x^2<1 which the same as (1).

The second says that -x^2 < 1 <x> -1 which can be any value since x^2 is always greater than -1. So (2) alone is INSUFF

Answer A.

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by lvincy » Wed Jun 25, 2008 11:31 am
2) |x| <1> 1 then statement is false
IF x < 0 then also statement is false.


This will be true only for positive fraction numbers between 0 and 1.
So B is sufficient to say |x| < 1


Ans D.

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by atlantic » Wed Jun 25, 2008 1:04 pm
Of course lvincy. My mistake.

B says that modX cannot less than 1, so in fact it answers tha question.

Answer is D.