Square root concept in GMAT

[sunnyjohn]

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?

[Frankenstein]

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.

[BlindVision]

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

[tpr-becky]

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

[sunnyjohn]

Thanks everyone..