1, continuous elementary function, to find the limit in the definition domain, you can directly substitute this point to get the limit value, because the limit value of continuous function is equal to the function value of this point.

2. Eliminate zero factor (for 0/0 type) by using unit deformation.

3. Use the relationship between infinity and infinitesimal to find the limit.

4. Find the limit by using the property of infinitesimal.

5. The original formula can be simplified and calculated by using equivalent infinitesimal replacement to find the limit.

6. Use two limit existence criteria to find the limit, and some topics can also be enlarged and reduced, and then use the pinch theorem to find the limit.

7. Find the limit with two important limit formulas.

8. Use the left and right limits to find the limit (usually aimed at finding the limit value of discontinuous points).

9. Find the limit with L'H?pital's law.

Among them, the most commonly used methods are Lobida's rule, equivalent infinitesimal substitution and two important limit formulas.

When doing a problem, if it is the factor part of the numerator or denominator, and a constant value that is not 0 can be obtained in a certain process, we often directly replace it with a numerical value to simplify it. In addition, equivalent infinitesimal substitution can also be used to simplify, and then consider the law of Robida after simplification.