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1,f(x)=cos(2x-π/3)+2sin^2 x (1)求最小正周期及对称轴方程,
人气:174 ℃ 时间:2019-09-29 04:15:06
解答
f(x)=cos(2x-π/3)+2sin^2 x=cos2xcosπ/3+sin2xsinπ/3+1-cos2x=1/2cos2x+sin2xsinπ/3+1-cos2x=-1/2cos2x+sin2xsin(π-2π/3)+1=cos2π/3cos2x+sin2xsin2π/3+1=cos(2x-2π/3)+1所以最小正周期是π,对称轴方程是x=...我还想问下,若g(x)=(f(x))^2+f(x),那其值域怎么求?g(x)=(f(x))^2+f(x)=[cos(2x-2π/3)+1]^2+cos(2x-2π/3)+1=[cos(2x-2π/3)]^2+3cos(2x-2π/3)+2=[cos(2x-2π/3)+3/2]^2-1/4因为-1≤cos(2x-2π/3)≤1所以0≤[cos(2x-2π/3)+3/2]^2≤(1+3/2)^2=25/4所以g(x)其值域是[-1/4,6]
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