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algebra

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tanyatomar
 Post subject: algebra
 Post Posted: Mon Mar 05, 2012 2:34 pm 
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Students


Posts: 51
if x <0; then sqrt(-x|x|) is

1. -x
2. -1
3. 1
4. x
5. sqrt x

OA : -x....
i think it should be x... please do explain how it is -x

Tanya
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vijay.gmat2011
 Post subject: Re: algebra
 Post Posted: Mon Mar 05, 2012 8:38 pm 
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Students


Posts: 8
I agree - The answer should be x

I would have ruled out -x by looking at it because it's not negative unless we are dealing with imaginary numbers (which is out of scope for GMAT i believe)

Any thoughts?
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vijay.gmat2011
 Post subject: Re: algebra
 Post Posted: Mon Mar 05, 2012 8:40 pm 
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Students


Posts: 8
Btw - by it's I meant "Sqrt of a number". You might have guessed it (good practice for SC though ;-))
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shubham_sagijain
 Post subject: Re: algebra
 Post Posted: Wed Mar 07, 2012 3:02 pm 
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Posts: 27
Good question !

The answer is -X indeed..
tanya and vijay...it is given in the question stem that X < 0, so we know for that it is negative.

Also, we know that the value of sqrt (of any number) must be positive.So if your answer is X, then you are actually proving that the sqrt (-X|X|) is negative...since X is a negative quantity.
How can that be possible ? So the answer is -X !

Hope it helps...

Thanks,
Shubh
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RonPurewal
 Post subject: Re: algebra
 Post Posted: Wed Mar 07, 2012 8:28 pm 
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ManhattanGMAT Staff


Posts: 8179
read here:
if-x-0-then-sqrt-x-x-is-t903.html

this thread is now locked; if you have questions, post them there, not here. thanks.

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