Solve by factoring 9x^4-16=0

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.

Find the measure of angle y. round your answer to the nearest hundredth. ( type the numerical answer only) a right triangle is shown with one leg measuring 5 and another leg measuring 14. an angle across from the leg measuring 5 is marked y degrees. numerical answers expected!

Examine this system of equations. what integer should the second equation be multiplied by so that when the two equations are added together, the x term is eliminated? 3/4x+1/7y=6 1/8x-3/5y=16