[非常急]已知函数f(x)=根号3sin(wx+φ)-cos(wx+φ)(0
[非常急]已知函数f(x)=根号3sin(wx+φ)-cos(wx+φ)(0
∵函数f(x)=根号3sin(wx+φ)-cos(wx+φ)(00)
f(x)=√3sin(wx+φ)-cos(wx+φ)=2sin(wx+φ-π/6)
∵函数y=f(x)图像的两相邻对称轴的距离为π/2
∴函数y=f(x)图像的最小正周期为π,w=2
f(x)=2sin(2x+φ-π/6)
又为函数y=f(x)偶函数
∴φ-π/6=π/2,即,f(x)=√2cos2x
(1)f(π/8)=2cos2x=√2
(2)g(x)=2cos2(x-π/6)=2cos(2x-π/3)
2kπkπ+π/6
f(x)=√3sin(wx+φ)-cos(wx+φ)
=2*sin(wx+φ - π/6)
因为是偶函数,所以x=0时,sin(wx+φ - π/6)=1或-1,得φ=2π/3或-π/3
因为0函数y=f(x)图像的两相邻对称轴的距离为π/2,则周期为π
w>0,所以w=2π/π=2
所以f(x)==2*sin(2x+π/2)=2cos2x
1)、f(π/8)=2*cos(2*π/8)=2cos(π/4)=√2
2)、函数y=f(x)的图像向右平移π/6个单位,
则g(x)=2cos【2(x-π/6)】=2cos(2x-π/3)
单调递增区间:2x-π/3∈【2kπ+π,2kπ+2π】,即x∈【kπ+2π/3,kπ+7π/6】
单调递减区间:2x-π/3∈【2kπ,2kπ+π】,即x∈【kπ+π/6,kπ+2π/3】
(1)f(x)=根号3sin(wx+φ)-cos(wx+φ)=2Sin(wx+φ-π/6)
由于是偶函数,即f(x)=f(-x)
即2Sin(wx+φ-π/6)=2Sin(-wx+φ-π/6)
即SinwxCos(φ-π/6)+CoswxSin(φ-π/6)=-SinwxCos(φ-π/6)+CoswxSin(φ-π/6)
即SinwxCos(φ-π/6)=0
又Sinwx不恒等于0,所以Cos(φ-π/6)=0
又0f(x)=2Sin(wx+φ-π/6)=2Coswx
又函数y=f(x)图像的两相邻对称轴的距离为π/2,w>0
可知其周期为π
故w=2
所以f(x)=2Cos2x
f(π/8)=2Cos(π/4)=根号下2
(2)将函数y=f(x)的图像向右平移π/6个单位,得到y=g(x)的图像
可知g(x)=2Cos2(x-π/6)=2Cos(2x-π/3)
求递减区间,只需2kπ解得kπ+π/6递减区间:[kπ+π/6,kπ+2π/3]
f(x)=2(cos(π/3)sin(wx+φ)-sin(π/3)cos(wx+φ))
=2sin(wx+φ-π/3)
T=2*(π/2)=π
w=2π/T=2
f(x)是偶函数
只能取φ-π/3=π/2
φ=5π/6
f(x)=2sin(2x+π/2)=2cos2x
f(π/8)=2cos(π/4)=√2
g(x)=f(x-π/6)=2cos(2(x-π/6))=2cos(2x-π/3)
2kπ-πkπ-π/3