Could someone please show me how to do this problem step-by-step? I’m so confused :/
1 Answer
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sin4x=-2sin2x
2sin2xcos2x=-2sin2x
2sin2xcos2x+2sin2x=0
2sin2x (cos 2x + 1) =0
sin 2x (cos 2x + 1)=0
sin x =0 OR cos 2x + 1=0
sin x = 0 for x=0 and x=pi in the interval [0,2pi)
cos2x + 1 = 0 implies cos 2x = -1.
So 2x = pi or 3pi or 5pi etc
so x = pi/2, 3pi/2 only ones in [0,2pi)
Hence we have the 4 solutions: x=0, x=pi, x=pi/2, and x=3pi/2
