第一个算对了!第二个我书上的答案是e²/4+1/4=1/4(1+e²)
追答可能你上限打错了吧,1e什麽意思?
追问好意思!上限是个e,没有1!不好意思啊!
追答∫ xlnx dx = ∫ lnx d(x²/2) = (1/2)∫ lnx d(x²)
= (1/2)x²lnx - (1/2)∫ x² d(lnx)
= (1/2)x²lnx - (1/2)∫ x²(1/x) dx
= (1/2)x²lnx - (1/2)∫ x dx
= (1/2)x²lnx - (1/2)(x²/2) + C
= (1/2)x²lnx - (1/4)x² + C
= (1/4)x²(2lnx - 1) + C
代入上下限得:
= (1/4)(e²)[2ln(e) - 1] - (1/4)(0)
= (1/4)(e²)(2 - 1)
= e²/4
还有意见不?你要有鉴别能力,不只是光信答案就可以。
谢谢了啊!一会给你发过去几道题!帮忙解答一下!