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Please help me with this little algebra problem

  1. Sep 12, 2011 #1
    1. The problem statement, all variables and given/known data

    Simplify the following, giving the result without fractional indices:

    [(x^2 -1)^2 * √(x+1)]/ (x-1)^3/2

    2. Relevant equations
    3. The attempt at a solution

    There are no common bases to add the indices and no common indices to multiply out the bases so I tried this and got it wrong, please show me where though:

    [(x-1) (x+1)]^2 * (x+1)^(1/2)] / (x-1)^(3/2)

    =[(x-1)^2 * (x+1)^2 * (x+1)^(1/2)] / (x-1)^(3/2)

    multiplied the indices by 2 and got rid of the fractions

    =[(x-1)^4 * (x+1)^4 * (x+1)] / (x-1)^3

    = (x-1) *(x+1)^5

    But my textbook says it is :( x + 1 )^2 √( x^2 - 1 )

    Thank You.
  2. jcsd
  3. Sep 12, 2011 #2


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    Homework Helper
    Gold Member

    You effectively squared the original problem. Now you need to un-square your result.
  4. Sep 13, 2011 #3


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    Science Advisor

    "Without fractional indices" just mean you need to use the square root:
    [tex](x- 1)^{3/2}= \sqrt{(x-1)^3}[/tex]
  5. Sep 14, 2011 #4
    Thank You, Everyone.
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