解方程2sin3x·cos2x+2sin^2x=0

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解方程2sin3x·cos2x+2sin^2x=0

解方程2sin3x·cos2x+2sin^2x=0
解方程2sin3x·cos2x+2sin^2x=0

解方程2sin3x·cos2x+2sin^2x=0
左边= 2×(sin(x))^3×(1-2(sin(x))^2)+2×(sin(x))^2
= 2×(sin(x))^3-4×(sin(x))^5+2×(sin(x))^2
= [sin(x)-2×(sin(x))^3+1]2×(sin(x))^2
=(sin(x)-1)×(-2×(sin(x))^2-2×sin(x)-1)×2×(sin(x))^2=0
∵-2(sin(x))^2-2sin(x)-1