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Integrate[1/Sqrt[(a^2 - x^2)^3], x] ==
(x*(a^2 - x^2))/(a^2*Sqrt[(a^2 - x^2)^3])

                 1
Integrate[----------------, x] == 
                 2    2 3
          Sqrt[(a  - x ) ]

        2    2
    x (a  - x )
-------------------
 2        2    2 3
a  Sqrt[(a  - x ) ]