Because mathematics in high school and junior high school are completely different.

Don't think that a good junior high school is enough.

First, your learning environment has changed, and second, your learning content has changed.

Many people say that the function is difficult, and I think it is very simple.

First of all, please understand that this piece is very important, because all future knowledge should be based on it, which is of course why it is put at the beginning, so you must learn well here, which means half the battle and a lot of effort will be saved in future study.

Secondly, there are only a few knowledge points in this piece.

Include definition domain, value domain, monotonicity, periodicity, etc.

I didn't learn well in this respect either, and later I found a trick.

As long as you do a special training for each piece.

Find relevant questions to train and do more, and you will find that there are only a few questions.

One by one. Don't worry. Know a type and solve one.

Therefore, relatively speaking, the thinking is clear.

After all, you should start with more special training, I hope it will help you.

I have a good knowledge of high school mathematics.

You can ask me if you don't understand anything.

I will definitely give a good answer.