1. The problem statement, all variables and given/known data cos(4x)(6+2a)+12a+8b=-20 find values for a, b. Then check the values and state which values of x would not have been sufficient checks. 2. Relevant equations Complex number equations 3. The attempt at a solution I've simplified it down to this from a harder problem but I can't get any further, putting it into wolfram gives me a=-3 and b=2 but I have no idea how that was worked out. Thanks in advance for any help!