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|x-z|+|x|=|z|?

Expert replies
Source: — Data Sufficiency |

by Anurag@Gurome » Tue Feb 28, 2012 7:46 pm
dreamv wrote:If zy<xy<0, is |x-z|+|x|=|z|?

1) z<x
2) y>0
zy < xy < 0

Case 1: If y < 0, then z > x > 0
z > x implies |x - z| = -(x - z) = z - x, since both x and z > 0
This means |x| = x and |z| = z
So, |x - z| + |x| = z - x + x = z
Hence, |x - z| + |x| = |z| is true.

Case 2: If y > 0, then z < x < 0
z < x implies |x - z| = x - z, since both x and z < 0
This means |x| = -x and |z| = -z
So, |x - z| + |x| = x - z - x = -z
Hence, |x - z| + |x| = |z| is true.

From both the cases, we can conclude that |x - z| + |x| = |z| is true. But we could conclude the answer without using either statement. Statements 1 and 2 are given in the question itself. What is the source of this question?
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

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by bubbliiiiiiii » Wed Feb 29, 2012 7:59 am
Case 1: If y < 0, then z > x > 0
Hello Sir,

Could you please elaborate the above statement?
Regards,

Pranay
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by dreamv » Wed Feb 29, 2012 9:52 am
Thank you Anurag. Source is GMATPrep. So answer is D, right? 1) z<x falls into case 2. 2) y>0 falls into case 2.
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