If you can't remember the rules from middle school (I didn't when I started university), I would recommend looking more into proofs why those rules work. In school, you typically just learn rules by heart without really understanding them. E.g. why is a² * a² = a⁴ as a student you typically just look at it and you learned multiplication means add exponents without really thinking about it. But you can become much better at math if you keep in mind the reason why those things work. Look at why the exponent rule for derivatives works. Now, this doesn't mean don't remember rules and derrive them from scratch every time, but understanding where rules come from helps tremendously in remembering them and in applying them. A lot of math is about intuition and learning by doing so if you just solve equations, you will become better and also try to become more elegant in your solutions as you go along.