SOLUTION: Solve algebraically :
3 cos2x+cosx+1=0
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Question 941795: Solve algebraically :
3 cos2x+cosx+1=0
Answer by srinivas.g(540) (Show Source): You can put this solution on YOUR website!
3cos2x+cosx+1=0
let assume cos(x) =t
the above equation becomes as follows
possible solotutions
either (3t+2)=0 or (2t-1)=0
3t=-2 2t =1
t= -2/3 t= 1/2
Hence t= -2/3 or 1/2
but t= cos(x)
hence cos(x) = -2/3 or 1/2
x= 131.81 degrees or 60 degrees
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