1. Limit and continuity: Limit is the foundation of calculus, but many students will encounter difficulties in the learning process. It takes some time and practice to understand the concept of limit, its solution and the conditions for its existence. In addition, continuity is also an important but difficult concept.
2. Derivative and differential: Derivative is a tool to describe the rate of change of a function, while differential is the geometric meaning of derivative. Understanding the definition and law of derivative and applying derivative to solve practical problems require certain abstract thinking ability.
3. Integral and definite integral: Integral is another important branch of calculus, which describes the cumulative effect of a function in a certain interval. It takes a lot of practice to understand the concepts of indefinite integral and definite integral, the solution of integral and the application of integral to solve practical problems.
4. Multivariate function calculus: Multivariate function calculus is an important extension of calculus, involving the relationship between multiple variables. It is a challenge to understand the limits, derivatives and integrals of multivariate functions and their relationships.
5. Series: Series is the sum of infinite numbers and is widely used in mathematics. Understanding the concept of series, judging whether series converges or not, and solving the sum of series are all important difficulties.