Your math grades are unstable because you are not solid in your studies. In fact, carelessness is caused by poor study. So here's what you should do:
1) be open-minded: in the usual learning process, you should do whatever is difficult or easy. And try your best not to lose points. Don't think you are smart, just take a look at the simple questions. Do it yourself In fact, what really loses points is the easy question.
2) Help others: In the process of learning, communicate with others as much as possible. Especially when other students ask you for help, you should explain it to others seriously and happily. In this process, you benefit the most.
3) Reflection: timely recognize the error-prone knowledge points encountered in learning. Think more and practice more. Try to hold on tight.