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Square root concept in GMAT

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Square root concept in GMAT

by sunnyjohn » Sat Jul 30, 2011 8:11 am
Hi,

I was reading Master the GMAT maths concepts about square root. According to it, GMAT only consider positive value of square root. For example-

4th root of 16 = -2 or 2

GMAT only consider 2. Isn't it wierd ?

Can any expert please comment on this?
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by Frankenstein » Sat Jul 30, 2011 8:28 am
Hi,
It is not just on GMAT. Square root of number is always the positive one. Never consider the negative root.
sqrt(4) = +2 only, not 2 or -2.
Some of the school books might have given both roots. But, it is incorrect.
But, if you are given x^2 = 4, find x. The answer would be x =+2 or -2.
Cheers!

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by BlindVision » Sat Jul 30, 2011 3:32 pm
If I may add the obvious, no number when multiplied an even number of times will yield a negative number.

However, for odd roots (cube, 5th, 7th, etc.) the root will have the same sign as the base:

3 sqrt(-27) = -3 not +/- 3
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by tpr-becky » Sat Jul 30, 2011 8:04 pm
If the GMAT puts the number under the square root then they only consider the positive root.

Thus sqrt25 = 5

However if the gmat says the square of a number is -- then you need to consider positive and negative.

Thus x^2 = 25 means that x = 5 or -5
Becky
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by sunnyjohn » Sun Jul 31, 2011 8:44 pm
Thanks everyone.. :)
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