(adsbygoogle = window.adsbygoogle || []).push({}); 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!

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# Complex number question involving de Moivre identity

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