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is |x| < 1?

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Re: is |x| < 1?

by logitech » Wed Nov 05, 2008 5:30 pm
erukumk wrote:
logitech wrote:
erukumk wrote:is |X| < 1?
1) |X+1|=2|X-1|
2)|X-3|!=0
Question can be paraphrased as:

Is X between -1 and + 1 ?

1) |X+1|=2|X-1|

if we take the square of both side and re-arrange it:

3X^2 - 10X + 3 = 0

X = 1/3 or X = 3

INSUF

2) IX-3|!=0

|X-3|!=0 , 0! = 0

Means that X=3

3 is not between -1 and + 1

Sufficient

Hence, B
for statement 1: can you tell me why did you square on both sides??
When two absolute values are equal to each other, you can square both sides , because no matter it is positive or negative, you will have a POSITIVE result.
LGTCH
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by erukumk » Wed Nov 05, 2008 6:55 pm
thanks for the explanation
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