If you are looking for a general method or asking about something more conceptual then say so clearly in the body of the question.
Instead of stating a specific instance of your general problem and then rambling on a bit about it, as in your first, state clearly what you are after:
I managed to solve the following problem, but I am wondering if there is a general method which can be used to solve all such problems.
Then state your specific instance of the problem. If you have a solution to this instance then it is probably helpful to give it in the question. This potentially helps people answering the problem, but also makes it clear that you are after more than a solution to this instance.
A similar idea can be applied to your third question. First state what you are after:
Something weird happened when I was playing around with L'Hôpital's rule, and I would like to understand it better. For example, consider the following problem:
Then state the problem etc. as you have done.
Also, as a side point, I got slightly confused and frustrated by the lack of full stops and capital letters in your questions, along with other things (0 not $0$, x not $x$, etc.). This can put off answerers. So if you do want more people to put in an effort to answer your questions then you should put in the effort to make them clear and smart and presentable.