Question

4cos^2(x) +4cosx=-1

Answer 1

you want to solve for x or what?

Answer 2

Yes

Answer 3

well using a simple substitution, let cos(x) = u so we have 4u^2+4u -1 = 0 and then using the quadratic formula ( i wont write this part because its too long) but you get u = 1/2 ====> cos(x) = 1/2 ===> cos^-1(1/2) = x so x = plus-or-minus π/3

Answer 4

Thank you I really appreciate all your help