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Integrate[Sqrt[a^2 - x^2]/x^4, x] ==
-((a - x)*(a + x))^(3/2)/(3*a^2*x^3)

                2    2
          Sqrt[a  - x ]
Integrate[-------------, x] == 
                4
               x

                  3/2
-((a - x) (a + x))
---------------------
          2  3
       3 a  x