Mathematics compulsory course from difficult to easy to sort.
Required 1: function.
Mathematics is the cornerstone of the whole senior high school, and it is also the first book spoken by almost every school.
After learning, you will find that the original mathematics has changed, and it is no longer something that can be done well by understanding formulas and conclusions.
Mainly abstract. Some topics look at the results of search software, which is completely confusing.
The most difficult part of high school mathematics is derivative, followed by conic curve, inequality, elementary function, series and plane vector.