put : x² + 1/x² = t

        (2x  - 2)/x³ .dx = dt

         2(x⁴-1)x³.dx=dt

I = integral of { (x⁴-1)/x²*x(x²+1+(1/x²)) .dx  }

   = integral of { (1/2.(t)^1/2 ).dt }

   = 1/2 * 2*(t)^1/2 + C

   = (x² + (1/x²) +1)^1/2  + C

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