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### L'Hôpitals rule

The limit of a quotient can be calculated with L'Hôpital's rule

when the function is indeterminate in that point.

##### Explanation

We start from the function

of which we have found that in the point *a* this function is indeterminate. We approach this point as a limit, so

This can be simplefied to

We play with the differentials *du* and *dv*, that gives

That looks like hocus pocus, but it shows directly what l'Hôpitals rule is all about