L'Hospital question

**EvLer** · Oct4-05, 01:03 AM

I was just wondering... it is used when the limit is of indetermined form: 0/0 or inf/inf, but is it valid to apply it to a "regular" limit? technically it seems to give the same answer...

**CarlB** · Oct4-05, 01:21 AM

If I recall, his rule was to the effect that the ratio of the limits, when the limits are 0 or $LaTeX Code: \\infty$ , is the ratio of the derivatives. That said, you certainly cannot apply it to a regular limit.

As an example, consider the limit:

Lim x->0 (cos(x)+3) /(x+4)

It is clear that the above limit is 4/5.

On the other hand,

Lim x-> 0 (-sin(x))/(1) = 0.

Carl

**EvLer** · Oct4-05, 01:30 AM

Oh, ok thanks...