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已知函数f(x)=2sin(π/4+x)^2-(根号3)2x-1,x属于r.(1)求f(x)的最值和最小正周期.
(2)若h(x)=f(x+t)的图像关于点(—π/6,0)对称,且t属于(0,π),求t值
人气:170 ℃ 时间:2019-08-21 10:42:42
解答
1)f(x)=2sin(x+π/4)^2-√3cos2x-1=-√3cos2x-[1-2sin(x+π/4)^2]
=-√3cos2x- cos(2x+π/2)
=-√3cos2x+sin2x
=2sin(2x-π/3)
最小值为-2,最大值为2
最小正周期为T=π
2)h(x)=f(x+t)=2sin(2x+2t-π/3)关于点(-π/6,0)对称
则2sin(2×(-π/6)+2t-π/3)=0
故2×(-π/6)+2t-π/3=kπ,t属于(0,π),
所以t= kπ/2+π/3,k∈Z.
t=π/3或5π/6.设p:x属于[π/4,π/2],q:f(x)-m的绝对值<3,若p是q的充分条件,求实数m的取值范围。谢谢。。当x属于[π/4,π/2]时,f(x) =2sin(2x-π/3)2x-π/3属于[π/6,2π/3]sin(2x-π/3)属于[1/2,1]所以f(x) 属于[1,2]若p是q的充分条件,则有If(x)-mI<3-3
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