摘要：The limit idea is the basic idea of calculus. Almost all concepts in mathematical analysis are inseparable from the limit, but the limit is a concept that is difficult to understand accurately. By assuming that there is a certain point closest to the limit value, this paper provides a reasonable explanation for the infinitesimal paradox and a new answer to the question why the limit value is accurate in teaching. At the same time, this method is applied to the derivative and used to understand a common practical problem in mathematics. The analysis shows that this method is effective for the accurate understanding of limit problems.
