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Flash card

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tuichats
 Post subject: Flash card
 Post Posted: Thu Jun 09, 2011 1:06 pm 
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Students


Posts: 14
I saw this on one of the flash cards for number properties"WE ARE NOT ALLOWED TO TAKE AN EVEN ROOT OF A –VE # THEREFORE X MUST BE POSITIVE."
Can we take a odd root of a negative # then?
Thanks!
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varun_783
 Post subject: Re: Flash card
 Post Posted: Thu Jun 09, 2011 4:01 pm 
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Course Students


Posts: 263
Hi tuichats,

Yes, I think odd roots are ok because odd roots preserve the sign.

cube root of 8 is 2 and cube root of -8 is -2
-2 x -2 x -2 = -8

However, for even roots of negative numbers we have to use the concept to an imaginary number, which is outside the scope of GMAT

Regards

Sunil
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jnelson0612
 Post subject: Re: Flash card
 Post Posted: Sun Jun 12, 2011 10:51 pm 
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ManhattanGMAT Staff


Posts: 1857
Once again, Sunil is correct. :-)

_________________
Jamie Nelson
ManhattanGMAT Instructor
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tuichats
 Post subject: Re: Flash card
 Post Posted: Mon Jun 13, 2011 12:14 pm 
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Students


Posts: 14
Thanks Guys! This totally makes sense..
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RonPurewal
 Post subject: Re: Flash card
 Post Posted: Tue Jun 14, 2011 7:49 am 
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ManhattanGMAT Staff


Posts: 7146
tuichats wrote:
Thanks Guys! This totally makes sense..


glad it helped.
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