f(x)= (4cos (x) -cos (3x))^2 + (3sin (x) -sin (3x))^2

f(x) has to be simplified to the form: f(x)= a cos ^2 (2x) + b cos (2x) + c where a,b,and c are real numbers.

(1)a= - 2

(2)a+b+c=9

(3)M>16

(4)m< 0

(5)M+m<25

So I have this problem, and it has me absolutely stumped.

help?

thanks

-Kaplac