1. Arithmetic of limit: In the process of finding limit, we need to master all kinds of arithmetic of limit, such as four operations, compound function, trigonometric function and so on. Although these rules seem simple, they may encounter some problems in practical application, such as the comparison of infinitesimal quantities and the treatment of zero factors.
2. Existence of limit: Sometimes, we will encounter some special functions whose limit does not exist. In this case, we need to use L'H?pital's law, pinch theorem and other methods to judge whether the limit exists.
3. Skills of finding the limit: In the process of finding the limit, we need to use some skills to simplify the calculation process. For example, we can use Taylor formula to expand a complex function into a polynomial, thus simplifying the process of finding the limit. In addition, we can also use L'H?pital's law and pinch theorem to solve the limit.
4. Application of limit: Seeking limit is not only to get a numerical result, but more importantly, to be able to apply what you have learned to practical problems. This requires us to accumulate experience in the learning process and improve our ability to solve problems.
In a word, limit is an important and challenging subject in higher mathematics. If we want to master this knowledge well, we need to work hard in the learning process and overcome all kinds of difficulties and challenges.