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marasofia1616
Group Title
Find all solutions to the equation in the interval [0, 2π).
cos 2x  cos x = 0
 one year ago
 one year ago
marasofia1616 Group Title
Find all solutions to the equation in the interval [0, 2π). cos 2x  cos x = 0
 one year ago
 one year ago

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hieuvo Group TitleBest ResponseYou've already chosen the best response.0
so, cos2x=cosx, I think x is in those special angles
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.2
use identity : cos2x=2cos^2 x  1
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.2
so, we have a quadratic equation in form cosx, 2cos^2 x  1  cosx = 0 or 2cos^2 x  cosx  1 = 0 can u factor out it
 one year ago

marasofia1616 Group TitleBest ResponseYou've already chosen the best response.0
ok I get cos x(2 cos x1)=1
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.2
np, it should be (2cosx + 1)(cosx  1) = 0
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.2
now, for zeroes take each factors be zero, so 2cosx+1=0 or cosx1=0 solve for x
 one year ago

marasofia1616 Group TitleBest ResponseYou've already chosen the best response.0
ok I got the solutions 0, 2pi/3 and 4pi/3
 one year ago

marasofia1616 Group TitleBest ResponseYou've already chosen the best response.0
thank you
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.2
but, i miss one root :)
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.2
looks 0 be same for 2pi, right ?
 one year ago

marasofia1616 Group TitleBest ResponseYou've already chosen the best response.0
I got the answer right
 one year ago
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