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CAT 3: Absolute Range

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GMAT85
 Post subject: CAT 3: Absolute Range
 Post Posted: Sat Jul 12, 2008 8:29 pm 
Is |x| < 1 ?

(1) |x + 1| = 2|x – 1|
(2) |x – 3| > 0

I solved this problem a little differently. Can this problem be solved the following way?
Rephrase the question as "Is x <1?" or "Is x > -1?" or “Is -1 < x < 1?”

Statement 2. Not Sufficient! x>3 or x<3; therefore x is anything but 3.

Statement 1. Not Sufficient! When x>0 , (x + 1) = 2(x –1). This gives x=3.
When x<0 , -(x + 1) = -2(x –1). This gives x=1/3.
3rd scenario: -(x + 1) = 2(x –1). This gives x=1/3.
So, x=1/3 or 3. Insufficient to solve the problem.

Combining statement (1) and (2). x cannot equal 3 according to statement (1). x equal 1/3 or 3. Therefore, x=1/3. This is sufficient to answer the question.

Answer: C

I am not so good at absolute value questions. So please suggest the correct way of doing this problem.
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Maverick
 Post subject:
 Post Posted: Sun Jul 13, 2008 1:56 am 
Is |x| < 1 ?

(1) |x + 1| = 2|x – 1|
(2) |x – 3| > 0

(1) Taking + sign, x+1=2x-2 => -x = -3 => x=3
Taking -sign, x+1=-2x+2 => 3x=1 => x=1/3
Insufficient.

(2) |x – 3| > 0
So, x<>3. Insuff.

Combining: x=1/3. Suff.
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RonPurewal
 Post subject:
 Post Posted: Sat Jul 19, 2008 12:30 am 
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ManhattanGMAT Staff


Posts: 7146
ha, this problem has been posted on about 4 different threads in the space of a week. i understand it's hard to search for problems whose statements consist largely of mathematical symbols, but you should at least try.

http://www.manhattangmat.com/forums/abs ... t3648.html
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