According to the order from easy to difficult, I think it is linear algebra, advanced mathematics and discrete mathematics;

Advanced mathematics is easy to learn, which is closely related to high school mathematics, and discrete mathematics is abstract and difficult to get started;

According to the thickness of the book: discrete mathematics is the thinnest, linear algebra is the most important, and advanced mathematics is the thickest;

There are space vectors in advanced mathematics, which can be used for reference, but it is of limited help to high school space vectors. In fact, the space vector of high school is not very difficult. A vector is obtained by vertically establishing a spatial rectangular coordinate system, writing the coordinates of related points, and subtracting the starting point coordinates from the end point coordinates. The product of two vectors is the sum of the products of three corresponding coordinates. ......