It belongs to the category of higher mathematics. When x takes a certain value and substitutes it into a function or expression, it may calculate a certain value, or it may not be substituted at all, because there are unreasonable situations such as zero denominator when substituting. However, when x tends to this value, the calculated value tends to a fixed value more and more every time, or infinitely closer to this fixed value. Suppose the limit of this function exists at this point.

Conceptual characteristics

1, two important limits: limit is a basic concept in calculus, which refers to such a changing trend and the value (limit value) that the variable gradually tends to be stable in a certain changing process.

2. The concept of limit was finally strictly expounded by Cauchy and Wilstrass. In modern mathematical analysis textbooks, almost all basic concepts (continuity, differentiation and integration) are based on the concept of limit.