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mgarcia634
 3 years ago
Find all solutions in the interval [0, 2π).
cos2x + 2 cos x + 1 = 0
mgarcia634
 3 years ago
Find all solutions in the interval [0, 2π). cos2x + 2 cos x + 1 = 0

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mgarcia634
 3 years ago
Best ResponseYou've already chosen the best response.0cos^2 x+ 2 cos x +1=0

cwrw238
 3 years ago
Best ResponseYou've already chosen the best response.1this is a quadratic equation which will factorise

Stiwan
 3 years ago
Best ResponseYou've already chosen the best response.1\[\cos²(x) + 2\cos(x) + 1 = (\cos(x) + 1)²\] Hence the roots are all x out of [0,2pi) for which cos(x) = 1. pi and pi

Stiwan
 3 years ago
Best ResponseYou've already chosen the best response.1Sorry, of course it's just + pi as there are no negative numbers in this interval

cwrw238
 3 years ago
Best ResponseYou've already chosen the best response.1what about 0 as a solution?

mgarcia634
 3 years ago
Best ResponseYou've already chosen the best response.0the answer choices are a) x=2pi B)x=pi c) x=pi/4, 7pi/4

cwrw238
 3 years ago
Best ResponseYou've already chosen the best response.1are you sure you have the correct question is it cos 2x or cos^2 x ?

Stiwan
 3 years ago
Best ResponseYou've already chosen the best response.1It's B) x = pi as in my answer.

cwrw238
 3 years ago
Best ResponseYou've already chosen the best response.1in that case the answer is as Stiwam said
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