A savings account earns 8% interest each year, compounded quarterly (4 times a year). If a person invests $100 and makes no further deposits or withdrawals, what is the balance in the account after 3 years?

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.