Hu yuan's math class has free videos to listen to online. In Mr. Hu Yuan's class, from the basics to the key and difficult points, first teach the basic knowledge, from the difficult to the easy, step by step, instead of rigidly teaching formulas and reasoning methods, interspersed with relevant examples, and finally provide problem-solving ideas, which will enable you not only to learn formulas, but also to learn to answer corresponding questions and the same type of problem-solving ideas. You can listen to the teacher several times when you encounter difficult parts. Hu Yuan, male, doctor, professor and doctoral supervisor of China University of Science and Technology.