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    I'm getting quite confused with fractional indices because while I "know" that x ^a/b = (b root x) ^a - I just can't get my head around why (sorry about the attempted use of roots and indices). I'm normally pretty good at maths so not being able to understand this is really quite frustrating. If I can avoid having to use that rule by choosing to multiply out the indices then I would but I'm worried in case I get given just a number with a fractional index and told to simplify. I find it really hard to learn something if I don't understand it and I have a maths exam in a week - it got pulled forward (it was going to be after half term).

    Thanks in advance,
    Kirsty
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    (Original post by dancinglove)
    I'm getting quite confused with fractional indices because while I "know" that x ^a/b = (b root x) ^a - I just can't get my head around why (sorry about the attempted use of roots and indices). I'm normally pretty good at maths so not being able to understand this is really quite frustrating. If I can avoid having to use that rule by choosing to multiply out the indices then I would but I'm worried in case I get given just a number with a fractional index and told to simplify. I find it really hard to learn something if I don't understand it and I have a maths exam in a week - it got pulled forward (it was going to be after half term).

    Thanks in advance,
    Kirsty
    To understand why, work things out in the other direction.

    Are you happy that (x^a)^c = x^{ac}?

    Now suppose you start with the number x^{a/b}. What do you get if you work out (x^{a/b})^b?

    This should tell you how x^{a/b} is related to x^a.

    Similarly, think about (x^{1/b})^a
 
 
 
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