Question

Find all solutions in the interval [0, 2π).

cos2x + 2 cos x + 1 = 0

Answer 1

Factor. Set each factor equal to 0 and solve.

Answer 2

So how would the problem end up looking?

Answer 3

Can you factor this: x^2+2x+1

Answer 4

(x+1)(x+1)

Answer 5

replace x with cosx and you have it.

Answer 6

Oh. Thanks.

Answer 7

yw

Answer 8

Now, what would be the all solutions part of the question?

Answer 9

cos x + 1 =0
Subtract 1 from both sides.
Think of all the angles within the given interval that have that cosine.