Of course, graduate students in economics are almost the graduate students with the lowest threshold in the postgraduate field. The key is that their math is the simplest (math 3). Although there are three courses (advanced mathematics, linear algebra, probability theory, mathematical statistics), their knowledge is still relatively small.

Self-study college mathematics, my personal suggestion is to take courses such as advanced mathematics in college now, or read books by yourself and let friends or teachers who know mathematics give you guidance. First, you have an understanding of the whole modern mathematical theory. It is definitely not possible to build a car behind closed doors. Advanced mathematics and high school mathematics are almost completely different. With strong logic, it is a typical course that is becoming more and more difficult to get started. But don't be afraid, it just tells you not to take it lightly, because even the first part of advanced mathematics is not so easy to understand.

I suggest you find some lectures in the postgraduate forum or learning website (but postgraduate entrance examination is too difficult for you to watch at once), which will be highly popularized.

In addition, it should be noted that Mathematics III requires higher probability, which often needs to be combined with economic cases, and professional courses can not be ignored. Economics graduate students have little public expenses and the tuition is a bit expensive. I hope to be prepared.

If you have any questions about math, you can ask me directly. I believe I will give you a fairly good answer.

If you have a dream, pursue it. Don't be knocked down by reality. There are countless adult teachers every year, and college students can realize their dreams smoothly. Your conditions are still good.