The basic knowledge of the course is clearly explained, the topic is relatively simple, the teaching content is concentrated, the information is large, the cultivation of mathematical thinking logic is emphasized rather than mechanical operation, the class hours are more and the knowledge points are detailed. This course is suitable for students of all grades. The course can stimulate students' enthusiasm for mathematics, and even students with poor mathematical foundation can rekindle their hopes in the course. Teacher Hu Yuan's teaching philosophy is to let students do problems from the proposer's point of view and have "proposer's thinking". The course includes not only the explanation of basic knowledge, but also a large number of problem-solving skills and methods, so that students can quickly improve their problem-solving ability in the process of learning. Introduction to online courses: Online courses are the sum of the teaching contents and activities of a certain subject expressed through the Internet, and are a new manifestation of courses in the information age. Including the teaching content and network teaching support environment organized according to certain teaching objectives and teaching strategies. Among them, the network teaching support environment refers to the software tools, teaching resources and teaching activities implemented on the network teaching platform. The characteristics of online courses are interactivity, interest, openness, collaboration and autonomy.