∫(x+2)/[(2x+1)(x^2+x+1)]dx
1个回答

设:(x+2)/[(2x+1)(x^2+x+1)]

=A/(2x+1)+(Bx+C)/(x^2+x+1)

那么:x+2=A(x^2+x+1)+(2x+1)(Bx+C),求得:A=2,B=-1,C=0

∫(x+2)/[(2x+1)(x^2+x+1)]dx

=∫[2/(2x+1)-x/(x^2+x+1)]dx

=ln|2x+1|-(1/2)∫[(2x+1-1)/(x^2+x+1)]dx

=ln|2x+1|-(1/2)ln(x^2+x+1)+(1/2)∫[1/(x^2+x+1)]dx

=ln|2x+1|-(1/2)ln(x^2+x+1)+(1/√3)arctan[(2x+1)/√3]+C