求dx/[ x*(x^2+1) ]的积分

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求dx/[ x*(x^2+1) ]的积分
求dx/[ x*(x^2+1) ]的积分

求dx/[ x*(x^2+1) ]的积分
∫1/[x(x^2+1)] dx,d(x^2)=2xdx
=(1/2)∫1/[x^2*(x^2+1)] d(x^2)
=(1/2)∫1/x^2 d(x^2)-(1/2)∫1/(x^2+1) d(x^2)
=(1/2)∫1/x^2 d(x^2)-(1/2)∫1/(x^2+1) d(x^2+1)
=(1/2)ln(x^2)-(1/2)ln(x^2+1)+C
=(1/2)ln[x^2/(x^2+1)]+C
或=(1/2)*2lnx-(1/2)ln(x^2+1)+C
=lnx-(1/2)ln(x^2+1)+C