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令x=t²,dx=2tdt
原式=∫[2t/(1+t³)]dt=2∫[t/(1+t)(1-t+t²)]dt
=(2/3)∫[(1+t)/(1-t+t²)-1/(1+t)]dt
=(-2/3)ln|1+t|+(1/3)∫[(2t+2)/(t²-t+1)]dt
=(-2/3)ln|1+t|+(1/3)∫[(2t-1)+3]/(t²-t+1)dt
=(-2/3)ln|t+1|+(1/3)∫[(2t-1)/(t²-t+1)]+∫[1/(t²-t+1)]dt
=(-2/3)ln|t+1|+(1/3)∫[1/(t²-t+1)]d(t²-t+1)+∫[1/(t-1/2)²+(√3/2)²]dt
=(-2/3)ln|t+1|+(1/3)ln(t²-t+1)+(2/√3)arctan[(2t-1)/√3]+C
将t=√x代入上式即得
原式=∫[2t/(1+t³)]dt=2∫[t/(1+t)(1-t+t²)]dt
=(2/3)∫[(1+t)/(1-t+t²)-1/(1+t)]dt
=(-2/3)ln|1+t|+(1/3)∫[(2t+2)/(t²-t+1)]dt
=(-2/3)ln|1+t|+(1/3)∫[(2t-1)+3]/(t²-t+1)dt
=(-2/3)ln|t+1|+(1/3)∫[(2t-1)/(t²-t+1)]+∫[1/(t²-t+1)]dt
=(-2/3)ln|t+1|+(1/3)∫[1/(t²-t+1)]d(t²-t+1)+∫[1/(t-1/2)²+(√3/2)²]dt
=(-2/3)ln|t+1|+(1/3)ln(t²-t+1)+(2/√3)arctan[(2t-1)/√3]+C
将t=√x代入上式即得
追问
您好,谢谢回答。
少了一个字母
应该是
1/(1+AX^(2/3))
A为常数,谢谢高手了
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