Question

L'Hopital... need some light on it

Answer 1

What is the question? In general L'Hopital's rule lets you repetitively differentiate indeterminate limits until you get a limit that is not indeterminate. If you have a specific question I may be able to clarify more.

Answer 2

http://www.math.hmc.edu/calculus/tutorials/lhopital/

Answer 3

my teacher told me that it isnt applicable every where where there is 0/0 or infinite /infinite.. so i have to be cautious.. but he didnt told me the case of 0/0 or infinite/infinite where it doesnt apply

Answer 4

Example 3: http://tutorial.math.lamar.edu/Classes/CalcI/LHospitalsRule.aspx

Answer 5

^^Ex 3 is: \[\lim_{x \rightarrow -\infty} xe^{x}\]

Answer 6

and when you manipulate it to \[\lim_{x \rightarrow -\infty} (e^{x})\div(1/x)\], in order to make it eligible for L'Hopital's rule, L'Hopital's rule doesnt work

Answer 7

L'Hôpital's Rule: If \(\dfrac{f(a)}{g(a)}\) for some constant \(a\) is indeterminate, then\[\Large \lim_{x\rightarrow a} \frac{f(x)}{g(x)} = \lim_{x\rightarrow a} \frac{\frac{d}{dx} f(x)}{\frac{d}{dx} g(x)}\]The differentiated form is often more easy to evaluate than the original.

Answer 8

L'Hôpital's Rule works in all cases of 0/0 and ∞/∞. That is to say the limit that you get will not be inaccurate, so you can always try it in those cases. As nolastudent points out above, though, in some cases it may not help.