已知函数f(x)=根号3sinxcosx+cosx^2,(1)求函数单调增区间

(2)函数图像关于直线x=x0对称,0<x0<1,求x0的值
2025-07-30 12:01:05
推荐回答(1个)
回答1:

解:
f(x)=(√3)sinxcosx+(cosx)^2
f(x)=cosx[(√3)sinx+cosx]
f(x)=2cosx[(√3/2)sinx+(1/2)cosx]
f(x)=2cosx[cos(π/6)sinx+sin(π/6)cosx]
f(x)=2cosxsin(x+π/6)
f(x)=sin(2x+π/6)+cos(π/6)
f(x)=sin(2x+π/6)+√3/2
1、f'(x)=2cos(2x+π/6)
令f'(x)>0,即:2cos(2x+π/6)>0
解得:kπ+π/6>x>kπ-π/3
即:f(x)的单调增区间是:x∈(kπ-π/3,kπ+π/6)
2、f(x)=sin(2x+π/6)+√3/2
令:sin(2x+π/6)=±1,即:2x+π/6=±π/2
解得:x=π/6,或:x=-π/3
因为0<x0<1,所以:x0=π/6