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DS question: GMAT prep: Is sqrt((x-5)^2) = 5-x ?

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chandanthakur
 Post subject: DS question: GMAT prep: Is sqrt((x-5)^2) = 5-x ?
 Post Posted: Sun Sep 13, 2009 3:14 am 
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Students


Posts: 5
Is sqrt((x-5)^2) = 5-x ?

(1) -x|x| > 0
(2) 5-x > 0
This questions already appeared in previous Manhattan GMATprep math post
I marked B
But GMATprep says answer is D i.e. "each statement alone is sufficient".
1 => x is negative => equation true always
2 => x<5 => equation true always

For me, it seemed statement 2 includes statement 1 also.

Is it just a way to trick or I am missing some explanation?
Thanks for replying!
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tpsharma2u
 Post subject: Re: DS question: GMAT prep: Is sqrt((x-5)^2) = 5-x ?
 Post Posted: Sun Sep 13, 2009 3:22 am 
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Posts: 9
hi,
why r u looking at the two sentences together...
as u have urself observed that two statement individually are sufficient ...ans is D..
even if two statements are exactly same ans wud be D
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chandanthakur
 Post subject: Re: DS question: GMAT prep: Is sqrt((x-5)^2) = 5-x ?
 Post Posted: Sun Sep 13, 2009 6:00 am 
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Students


Posts: 5
tpsharma2u wrote:
hi,
why r u looking at the two sentences together...
as u have urself observed that two statement individually are sufficient ...ans is D..
even if two statements are exactly same ans wud be D


yeah!! I think you are right!! May be I was just confused with the subset type.
Thanks
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RonPurewal
 Post subject: Re: DS question: GMAT prep: Is sqrt((x-5)^2) = 5-x ?
 Post Posted: Sat Sep 26, 2009 1:54 am 
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ManhattanGMAT Staff


Posts: 6765
chandanthakur wrote:
I marked B
...
For me, it seemed statement 2 includes statement 1 also.


note that this is actually an impossible combination. if a MORE GENERAL statement is sufficient, then a fortiori any narrower statement will ALSO be sufficient.

so:
if statement 2 contains statement 1, then ELIMINATE (b) and (c).
if statement 1 contains statement 2, then ELIMINATE (a) and (c).
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RonPurewal
 Post subject: Re: DS question: GMAT prep: Is sqrt((x-5)^2) = 5-x ?
 Post Posted: Sat Sep 26, 2009 1:55 am 
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ManhattanGMAT Staff


Posts: 6765
by the way, for any onlookers, i've posted a complete explanation of this problem here:
is-sqrt-x-5-2-5-x-t5297.html
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chandanthakur
 Post subject: Re: DS question: GMAT prep: Is sqrt((x-5)^2) = 5-x ?
 Post Posted: Sun Sep 27, 2009 1:36 am 
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Students


Posts: 5
Thanks for your comment Ron.
RonPurewal wrote:
by the way, for any onlookers, i've posted a complete explanation of this problem here:
is-sqrt-x-5-2-5-x-t5297.html
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Ben Ku
 Post subject: Re: DS question: GMAT prep: Is sqrt((x-5)^2) = 5-x ?
 Post Posted: Thu Oct 22, 2009 3:14 am 
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ManhattanGMAT Staff


Posts: 824
Glad it helped.

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Ben Ku
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ManhattanGMAT
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