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Evaluate:`int(x^2-1)/((x^4+3x^2+1)tan^(-1)(x+1/x))dx`

Answer» `I=int(x^(2)-1)/((x^(4)+3x^(2)+1)tan^(-1)(x+(1)/(x)))dx`
`=int(1-(1)/(x^(2)))/((x^(2)+(1)/(x^(2))+3)tan^(-1)(x+(1)/(x)))dx`
Put `x+(1)/(x)=t`
` :. (1-(1)/(x^(2)))dx=dt " and " x^(2)+(1)/(x^(2))+3=t^(2)+1`
` :. I=int(dt)/((t^(2)+1)tan^(-1)t)="In"|tan^(-1)t|+C`
`="In"|tan^(-1)(x+(1)/(x))|+C`


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