What is the antiderivative of #x/(x^2+1) #? Calculus Introduction to Integration Integrals of Rational Functions 1 Answer Ratnaker Mehta Sep 21, 2016 #1/2ln(x^2+1)+C, or, ln (x^2+1)^(1/2)+C, or, lnsqrt(x^2+1)+C # Explanation: Let #I=intx/(x^2+1)dx#. Subst. #(x^2+1)=t rArr 2xdx=dt rArr xdx=dt/2#. #:. I=int1/t*dt/2=1/2int1/tdt=1/2ln|t|# #:. I=1/2ln(x^2+1)+C, or, ln (x^2+1)^(1/2)+C, or, lnsqrt(x^2+1)+C#. Answer link Related questions How do you integrate #(x+1)/(x^2+2x+1)#? How do you integrate #x/(1+x^4)#? How do you integrate #dx / (2sqrt(x) + 2x#? What is the integration of #1/x#? How do you integrate #(1+x)/(1-x)#? How do you integrate #(2x^3-3x^2+x+1)/(-2x+1)#? How do you find integral of #((secxtanx)/(secx-1))dx#? How do you integrate #(6x^5 -2x^4 + 3x^3 + x^2 - x-2)/x^3#? How do you integrate #((4x^2-1)^2)/x^3dx #? How do you integrate #(x+3) / sqrt(x) dx#? See all questions in Integrals of Rational Functions Impact of this question 3766 views around the world You can reuse this answer Creative Commons License