GMAT Prep - Roots

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by aditi_bc » Mon Dec 01, 2008 7:28 pm
This one should go to Math Flashcard :)

Rule:√(x^2) is equal to |x|

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by jnellaz » Tue Dec 02, 2008 10:27 am
This is actually one answer I actually don't understand. :( Isn't the absolute value of x divided by x equal to 1?

So if x = 9

|9|/9 = 1? Can anyone clarify?

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by iamcste » Tue Dec 02, 2008 1:35 pm
If x=9

LHS=√(x^2)=√(9^2)=+9 or -9

RHS=|x|=|9|=+9 or -9 ( as we dont know whether X is positive or negative)

LHS=RHS

√(x^2) is equal to |x|



Isn't the absolute value of x divided by x equal to 1?

No, we dont know that X is positive or negative

hence, it could be +1 or -1