0 函数f(x)=m·n+|m|.0 函数f(x)=m·n+|m|.x1,x2是集合M=【x|f(x

发布时间:2021-02-25 16:16:57

0 函数f(x)=m·n+|m|.0 函数f(x)=m·n+|m|.x1,x2是集合M=【x|f(x)=1】中任意两个元素,且|x1-x2|的最小值为π/2(1)求w,f(x)的对称轴,对称中心(2)x属于【π/2,π】时,求f(x)的零点(3)f(x)的图像向右平移π/4个单位,再各点的横坐

网友回答

f(x)=m·n+|m|
=cos²wx+sinwx(2√3coswx-sinwx)+1
=cos²wx-sin²wx+2√3sinwxcoswx+1
=√3sin2wx+cos2wx+1
=2sin(2wx+π/6)+1
x1,x2是集合M=【x|f(x)=1】中任意两个元素,且|x1-x2|的最小值为π/2
x1,x2是2sin(2wx+π/6)=0中任意两个元素,且|x1-x2|的最小值为π/2
∴2π/2w=T=π/2*2=π
w=1(1)f(x)=2sin(2x+π/6)+1
2x+π/6=π/2+kπ,k∈Z
x=π/6+kπ/2,k∈Z
f(x)的对称轴x=π/6+kπ/2,k∈Z
2x+π/6=0+kπ,k∈Z
x=-π/12+kπ/2,k∈Z
对称中心(-π/12+kπ/2,1),k∈Z
(2)f(x)=2sin(2x+π/6)+1
=0sin(2x+π/6)=-1/2
x∈【π/2,π】
2x+π/6∈【7π/6,13π/6】
2x+π/6=7π/6或11π/6
x=π/2或5π/6
(3)f(x)的图像向右平移π/4个单位
f(x)=2sin(2(x-π/4)+π/6)+1=2sin(2x-π/3)+1
再各点的横坐标变为原来的1/2
f(x)=2sin(4x-π/3)+1
再将图像乡下平移1个单位得到y=g(x)的图像
g(x)=2sin(4x-π/3)
x∈【0,π/4】
4x-π/3∈【-π/3,2π/3】
观察图像g(x)
有且只有一个实数解
只能在4x-π/3=π/2和4x+π/6∈[-π/3,π/3)两部分
∴g(x)+k=0
g(x)=-k
4x-π/3=π/2
k=-2或4x+π/6∈[-π/3,π/3)
-√3≤-k<√3,即:k∈(-√3,√3]
即:k=-2或k∈(-√3,√3]
======以下答案可供参考======
供参考答案1:|m|=1m·n=cos(wx)^2+√3sin(2wx)-sin(wx)^2=cos(2wx)+√3sin(2wx)=2sin(2wx+π/6),故:f(x)=m·n+|m|=2sin(2wx+π/6)+11f(x)=1,即:sin(2wx+π/6)=0,|x1-x2|的最小值是π/2即sin(2wx+π/6)的周期是π,即:2π/(2w)=π即:w=1,故:f(x)=2sin(2x+π/6)+1对称中心:2x+π/6=kπ,即:x=kπ/2-π/12即:(kπ/2-π/12,1),k∈Z对称轴:2x+π/6=kπ+π/2即:x=kπ/2+π/6,k∈Z2f(x)=2sin(2x+π/6)+1
=0,即:sin(2x+π/6)=-1/2x∈[π/2,π],故:2x+π/6∈[7π/6,13π/6]故:2x+π/6=7π/6或2x+π/6=11π/6即:x=π/2或5π/63f(x)图像向右平移π/4,即:f(x-π/4)=2sin(2x-π/2+π/6)+1=2sin(2x-π/3)+1横坐标压缩为原来的1/2,即:2sin(4x-π/3)+1故:g(x)=2sin(4x-π/3)x∈[0,π/4],故:4x-π/3∈[-π/3,2π/3]g(x)=-k
,即:sin(4x-π/3)=-k/2只有一个实数解即:-k/2=1,即:k=-2或:-√3/2≤-k/2<√3/2,即:k∈(-√3,√3]即:k=-2或k∈(-√3,√3]
供参考答案2:我看了下,就第三问跟楼上有差异。。。
以上问题属网友观点,不代表本站立场,仅供参考!