没有下限此谨？解法就是三角换元脱根号，换元x=tanu=∫1/tan³usecudtanu=∫cot²卖闷ucscudu=-∫cotudcscu=-cotucscu+∫cscudcotu=-cotucscu-∫(cot²u+1)cscudu=(-cotucscu-∫cscudu)/中扒弯2=(-cotucscu-ln|cscu-cotu|)/2+C
