First, use the continuity of the function to find the limit of the function.

In the process of finding the limit, if the function is continuous at a certain point, then the function value of that point can be directly substituted into the limit expression. This is because the continuous function is defined at any point in the domain, so the function value of this point can be calculated directly.

Second, using the property of infinitesimal to find the limit of function

1.？ The product of bounded function and infinitesimal is infinitesimal: this means that if one function is bounded and the other function is infinitesimal, then their product is infinitesimal. This property is very useful in finding the limit, because it can help us simplify the calculation.

2.？ The product of constant and infinitesimal is infinitesimal: this means that the product of any constant and infinitesimal is still infinitesimal. This property is often used to simplify the calculation of limit.

3.？ The addition, subtraction and multiplication of finite infinitesimals are still infinitesimals: this property shows that if there are finite infinitesimals to add, subtract and multiply, they are still infinitesimals. This property is very common in finding the limit of high numbers, because it can help us to deal with complex limit expressions.

Third, use L'H?pital's law to find the limit of the function.

Lobida rule is a common method to find the limit of indefinite form. For "?" Type and "?" We can use Robida's law to solve their limits. L'H?pital's law is derived from the definition and properties of derivative, and attention should be paid to the calculation and operation of derivative when using it.

Fourth, use the definition of definite integral to find the limit of function.

The definition of definite integral is a method of calculating integral, but we can also use the definition of definite integral to solve some special limit problems when solving the limit of height. Through the division, approximation and summation of functions, the complex limit problem can be transformed into definite integral calculation, thus simplifying the calculation process.