What are the Most Important Concepts You NEED to Learn in Algebra II?

Oh, also another thing that helped me was Kaplan’s 100 Key Math Concepts for the ACT. Just google that and it’ll pop up. It’s basically a crash course on things that you could see on the math. I went through it a few days before I took the ACT and started writing all of it down in a notebook so I would remember it. It was very helpful!