We all know l'hopital's rule ! But what is its proof ?!!
I guess that not all people know its proof ! Do they ?
Can any one give a proof for it ? Starting with the simplest one . L'hopital's rule is very important for calculating limits and was discovered by a french mathematician , M.l'hopital !
So I'm interested to know the proof of this great theorem. Isn't it a great theorem ? Thanks !