企源知识库

∫[3x²/(1+x²)]dx
【正确答案】：∫[3x²/(1+x²)]dx =3∫[(1+x²-1)/(1+x²)]dx =3∫(1-1/(1+x²)dx =3∫dx-3∫[1/(1+x²)]dx =3x-3arctanx+C.