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Lukecrayonz
Group Title
cos 4x  cos 2x = 0
Find all solutions to the equation in the interval [0, 2ð).
ð, pi/3 2pi/3 4pi/3 5pi/3, 0?
Is that correct?
 2 years ago
 2 years ago
Lukecrayonz Group Title
cos 4x  cos 2x = 0 Find all solutions to the equation in the interval [0, 2ð). ð, pi/3 2pi/3 4pi/3 5pi/3, 0? Is that correct?
 2 years ago
 2 years ago

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ganeshie8 Group TitleBest ResponseYou've already chosen the best response.1
\(\cos^4 x  \cos^2x = 0\) is the equation like above ?
 2 years ago

Lukecrayonz Group TitleBest ResponseYou've already chosen the best response.1
No, Cos(4x)cos(2x)=0
 2 years ago

Lukecrayonz Group TitleBest ResponseYou've already chosen the best response.1
@ganeshie8 no idea?:(
 2 years ago

ganeshie8 Group TitleBest ResponseYou've already chosen the best response.1
could u show me ur work
 2 years ago

Lukecrayonz Group TitleBest ResponseYou've already chosen the best response.1
cosx=cos(x+2kpi) Apply Cos C  Cos D formula Cos C  Cos D = 2sin(C+D)/2 Sin(DC)/2
 2 years ago

Lukecrayonz Group TitleBest ResponseYou've already chosen the best response.1
So 0, pi/3, 2pi/3, 4pi/3, 5pi/3 and ð
 2 years ago

Lukecrayonz Group TitleBest ResponseYou've already chosen the best response.1
@anas2000 can you help?:D
 2 years ago

ganeshie8 Group TitleBest ResponseYou've already chosen the best response.1
hmm that doesnt help me
 2 years ago

Lukecrayonz Group TitleBest ResponseYou've already chosen the best response.1
@UnkleRhaukus @robtobey
 2 years ago

ganeshie8 Group TitleBest ResponseYou've already chosen the best response.1
cos 4 x  cos 2 x = 0 2cos^2 2x1  cos 2x = 0 2u^2 u 1 = 0 (u1)(2u+1) = 0 u = 1; u = 1/2 cos 2x = 1 ; cos 2x = 1/2 2x = 0 ; 2x = pipi/3, 2x = pi + pi/3 x = 0 + npi; x = pi/3 + npi, x = 2pi/3 + npi x = 0, pi; x = pi/3, 4pi/3, x = 2pi/3, 5pi/3 so solutions will be : x = 0, pi/3, 2pi/3, 4pi/3, 5pi/3, pi looks you got the same solutions wid very less effort... !
 2 years ago

Lukecrayonz Group TitleBest ResponseYou've already chosen the best response.1
Thank you! Haha
 2 years ago

ganeshie8 Group TitleBest ResponseYou've already chosen the best response.1
np... yw :) good work !
 2 years ago
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