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DS: Absolute value

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ikaplan Really wants to Beat The GMAT!
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DS: Absolute value Post Sat Jul 21, 2012 8:03 pm
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    Is |x|=y-z

    (1) x+y=z
    (2) x<0

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    eagleeye GMAT Destroyer!
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    Post Sat Jul 21, 2012 8:22 pm
    ikaplan wrote:
    Is |x|=y-z

    (1) x+y=z
    (2) x<0
    We need to find if |x|= y-z.

    We know that |x| >=0. We also know that if x<0, |x| = -x.

    With that in mind, lets look at the statements.

    1. x+y = z
    => - x = y-z
    Now if x<0, |x|= y-z
    But if x>0, |x|= z-y

    Insufficient.

    2. x<0
    We know nothing about y,z. Insufficient.

    Together we know x<0, therefore -x =|x|, but from 1 we know that -x = y-z, hence |x| = y-z. sufficient

    Hence C is correct. Smile

    Thanked by: ikaplan

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