Luna die Spielerin
2021-07-24T15:30:52+00:00
请问老哥们这题的分子要怎么判断是无穷呀，套不进去反常积分的公式里，我看网上的解说直接怼分子就是无穷了。
[img]https://img.nga.178.com/attachments/mon_202107/30/-7Q8im9-e2piXcZ39T3cSzk-qo.jpg.medium.jpg[/img]
[img]https://img.nga.178.com/attachments/mon_202107/30/-7Q8im9-dyc4K1zT1kSg0-sg.jpg.medium.jpg[/img]
这红笔不都写不来了吗，ln(1+1/x)就是一阶无穷小啊
t取无穷大，小括号里就是零了，分子只剩右边的t，整个积分不就是无穷大了吗
[quote][pid=537044401,27847426,1]Reply[/pid] Post by [uid=37269009]秒速五公分[/uid] (2021-07-30 23:43):
t取无穷大，小括号里就是零了，分子只剩右边的t，整个积分不就是无穷大了吗[/quote]取无穷大的话，你要换元做，算出来是1/2
[img]https://img.nga.178.com/attachments/mon_202107/30/-7Q8im9-44boZ2aT3cSqo-zk.jpg.medium.jpg[/img]
[quote][pid=537043943,27847426,1]Reply[/pid] Post by [uid=63082606]唐牛1991[/uid] (2021-07-30 23:41):
这红笔不都写不来了吗，ln(1+1/x)就是一阶无穷小啊[/quote]老哥看3楼，给你写了，把x换成1/t
[quote][pid=537044811,27847426,1]Reply[/pid] Post by [uid=62259743]Ben_Gosugogosu[/uid] (2021-07-30 23:45):
取无穷大的话，你要换元做，算出来是1/2
......[/quote]你把dt漏了
[quote][pid=537045905,27847426,1]Reply[/pid] Post by [uid=37269009]秒速五公分[/uid] (2021-07-30 23:51):
你把dt漏了[/quote]没太懂。zsbd