Solve 2cos^2(w)+7cos(w)+5=0 for all solutions

Question

x = ____ where k ∈ Z

Answer 1

Let x = cos(w) then use the quadratic equation to solve for x. You will get two answers, one of which is not in the domain, [-1,1], for cosine, so can be ignored. The other repeats every 2kπ.

Answer 2