# Quod Erat Demonstrandum

## 2009/04/22

### 一些有關不能使用 l’Hôpital’s rule 的例子

Filed under: HKALE,Pure Mathematics — johnmayhk @ 9:31 上午
Tags: ,

Mathworld 也記下了兩個例子，參考參考

http://mathworld.wolfram.com/LHospitalsRule.html

Opened question: 應該如何教 l’Hôpital’s rule？

## 2 則迴響 »

1. May I know what the problem is for these few examples? Mathworld said “L’Hospital’s rule must sometimes be applied with some care, since it holds only in the implicitly understood case that g^'(x) does not change sign infinitely often in a neighborhood of infty.", but I tried to follow the proof of L’Hospital’s rule once more and don’t see where this is needed at all.

迴響 由 Soarer — 2009/04/25 @ 1:06 下午 | 回應