How do you find the integral of #dx/(1+x^2)#? Calculus Introduction to Integration Integrals of Rational Functions 1 Answer bp Oct 11, 2015 #tan^-1 x +C# Explanation: Let #x = tan theta#, so that #dx=sec^2 theta d theta# #int (1dx)/(1+x^2) # = #int (sec^2 theta d theta)/ sec^2 theta# #int d theta = theta +C# = #tan^-1 x +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 20895 views around the world You can reuse this answer Creative Commons License