POLYNOMIALS MULTIPLICATION (x^2-3) (4x+x^2-7)

Find the product of the polynomials in standard form

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.

Write the sine and cosine values of a, b, respectively, in the figure for (1) and (2) + explanation.

Solve for x and y: 217x + 131y = 913; 131x + 217y = 827