solve cos 3x+cos x-cos 2x=0?
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cos 3x + cos x - cos 2x = 0
[cos 3x + cos x ] - cos 2x = 0
2 cos [(3x + x)/2] .cos [(3x-x)/2] - cos 2x = 0
2 cos 2x . cos x - cos 2x = 0
cos 2x [ 2 cos x - 1 ] = 0
cos 2x = 0 or cos x = 1/2 = cos π/3
2x = (2n +1 )π/2 or x = 2mπ +- π/3
x = (2n + 1 ) π/4 or x = 2mπ +- π/3 ; where n , m ∈ I
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cos 3x + cos x - cos 2x = 0
[cos 3x + cos x ] - cos 2x = 0
2 cos [(3x + x)/2] .cos [(3x-x)/2] - cos 2x = 0
2 cos 2x . cos x - cos 2x = 0
cos 2x [ 2 cos x - 1 ] = 0
cos 2x = 0 or cos x = 1/2 = cos π/3
2x = (2n +1 )π/2 or x = 2mπ +- π/3
x = (2n + 1 ) π/4 or x = 2mπ +- π/3 ; where n , m ∈ I
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