I need help. How do i solve this?

Solve the system of equations. y= 2x y= x^2 - 15

Graph g(x)=2cosx . use 3.14 for π . use the sine tool to graph the function. graph the function by plotting two points. the first point must be on the midline and closest to the origin. the second point must be a maximum or minimum value on the graph closest to the first point.

Factor the polynomial. b^2 + 4b + 4