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# Indices question

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1. Why is it that when we normally square root a number the answer must have a +-, e.g. sqrt(9) = +-3, but that when there is a fractional index, the positive root is taken when square rooting, e.g. sqrt(9^3/2) = 3^3 = 27 and not +-3^3 = +-27. Sorry I'm just confused about it- thanks for any help
2. (Original post by 11owolea)
Why is it that when we normally square root a number the answer must have a +-, e.g. sqrt(9) = +-3, but that when there is a fractional index, the positive root is taken when square rooting, e.g. sqrt(9^3/2) = 3^3 = 27 and not +-3^3 = +-27. Sorry I'm just confused about it- thanks for any help
You don't take the negative square root. It would b wrong to say that . So .
If then sure, but it is important to realise that you are not just simply taking the square root of both sides.
This is a misconception many people have so please feel free to ask any more questions regarding the square root of you are confused about anything.
3. (Original post by B_9710)
You don't take the negative square root. It would b wrong to say that . So .
If then sure, but it is important to realise that you are not just simply taking the square root of both sides.
This is a misconception many people have so please feel free to ask any more questions regarding the square root of you are confused about anything.
Sorry but I still don't understand, if the square root of 4 is +-2 then why would you sometimes take the negative value and sometimes not, and how do you know if you should?
4. (Original post by 11owolea)
Sorry but I still don't understand, if the square root of 4 is +-2 then why would you sometimes take the negative value and sometimes not, and how do you know if you should?
That's what I'm saying, the square root of 4 is not +-2. and . The square root does not return a negative value.

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