In fact, unstable grades are normal, and there are many factors in it. Maybe it's your mentality, maybe your knowledge is a little shaky. I suggest you calm down first and face every exam and grade with a normal heart. Don't be too complacent when you do well in the exam, relax yourself, and don't feel sorry for yourself when you do badly in the exam. No matter how well students study, they sometimes fail the exam. Secondly, I suggest you make a summary and reflection on yourself. Find out several papers that did badly in the exam and see where the problems usually appear. Is there no skilled method for a certain question type or a certain knowledge point? Then the right medicine can get twice the result with half the effort. In addition, you can also discuss with some students who have good and stable math scores and see if they have any good suggestions and exam tips, which may also help you. I believe where there is a will, there is a way!

I hope I can help you!