Can someone help me I’m kinda stuck on this problem that I don’t really understand yet

Which of the expressions (on the photo document i inserted) together represent all solutions to the following equation? 8cos(12x)+4=-4 *the answer should be in degrees.* > i would like for someone to explain the process to find the solutions for this.

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?

What function has a range {yly< 5}? question on picture above^