Question

Find all solutions to the equation.
cos^2x + 2 cos x + 1 = 0 (4 points)

Answer 1

cos^2x + (1+1)cos x + 1 = 0

or,cos^2x + cos x + cos x + 1 = 0

or,cos x(cos x + 1) + 1 (cos x + 1) = 0

or, (cosx + 1) + (cosx + 1) = 0

either

cosx + 1 =0 or cosx +1 =0