y=3sin2x最大值的自变量x的集合

y=2sin2x+2cosx-3=-2cos2x+2cosx-1=-2（cosx-12）2-12≤-12．∴函数y=2sin2x+2cosx-3的最大值是−12．故选：C．

f(x)=sin2x-√3cos2x=2(1/2*sin2x-√3/2cos2x)=2(sin2xcosπ/3-cos2xsinπ/3)=2sin(2x-π/3)最小正周期T＝2π/2=π因为-1

2sinxcosx=sin2x,所以f(x)=2sin2x+3cos2x,令u=2x,f(x)=2sinu+3cosu,下面这个叫做辅助角公式：2sinu+3cosu=√(2^2+3^2)×[2sin

y=2sin2x+3cos2x=√13*sin(2x+a),其中cosa=2√13/13,a=arccos2√13/13最大值时2x+a=(2k+1/2)TT,k为整数,x=(k+1/4)TT+a/2

当cos(x/3)取得最大值,即cos(x/3)=1时,y取得最大值；cos(x/3)=1==>x/3=2kπ==>x=6kπ；k∈Z使最大的自变量x的取值集合为{x|x=6kxπ；k∈Z}

y=2(sinx)^2+2cosx-3=2-2(cosx)^2+2cosx-3=-2(cosx)^2+2cosx-1=-2(cosx-1/2)^2-1/2当cosx=1/2时,函数有最大值1/2,此时

y=2(sin2xcosπ/3+cos2xsinπ/3)=2sin(2x+π/3)所以最大值=2,最小值=-2周期=2π/2=π最大值时,2x+π/3=2kπ+π/22x=2kπ+π/6x=kπ+π/

函数y=3/2sin2x-1的最大值是__1/2____；周期是____π______-1≤sin2x≤1;最大值=3/2-1=1/2;周期=2π/2=π;

sin2x=-1时,(1)-3*（-1）+a=8,a=5（2）a=5时,y=-3sin2x+5的最小值为：-3+5=2（3）当sin2x=-1时,取得最大值为8,这时2X=-π/2+2Kπ,X=-π/

1）y=(1/2)(1/2cos2x+(√3)/2sin2x)+1=(1/2)sin(2x+π/6)+1所以y(max)=3/2时2x+π/6=2kπ+π/2即：{x|x=kπ+π/6,k∈Z}2)只

y=√3cos²x+1/2sin2x=√3/2(cos2x+1)+1/2sin2x=√3/2cos2x+1/2sin2x+√3/2=sin(π/3)cos2x+cos(π/3)sin2x+√

y=根号3乘cos平方x+1/2sin2x=根号3乘以二分之（1+cos2x）+二分之sin2x=sin（三分之π+2x）+二分之根号三当三分之π+2x=二分之π+2kπ,求出x,此时y最大=1+二分

y=cos2x-(√3)sin2x=-2[(√3/2)sin2x-(1/2)cos2x]=-2sin[2x-(π/6)].即y=-2sin[2x-(π/6)].∴该函数的最大值为2.

cos^2x=cos2x+1所以原式等于二分之根号三倍的（cos2x+1)+1/2sin2x化简得sin(2x+60)+二分之根号三最大值就是1+二分之根号三

cos是周期函数,且最小值为-1,故有,½x-π/6=2kπ-π,移项求出x=4kπ-5π/3此时y=-3/2*(-1)=3/2,达到最大值最小值同理

y=2sin(2x-π/3)最大值为2最小值为-2T=2π/2=π

max:2x+π/4=2kπ+π/22x=2kπ+π/4x=kπ+π/8min:2x+π/4=2kπ-π/22x=2kπ-3π/4x=kπ-3π/8

y=√3sin2x+cos2x=2(√3/2*sin2x+1/2*cos2x)=2(sin2xcosπ/6+cos2xsinπ/6)=2sin(2x+π/6)最大值=2此时2x+π/6=π/2+2kπ

解y=√3cos2x+sin2x+1=2(√3/2cos2x+1/2sin2x)+1=2(sin2xcosπ/3+cos2xsinπ/3)+1=2sin(2x+π/3)+1∵sin(2x+π/3)∈[

y=√3sin2x+cos2x=2(sin2xcosπ/6+cos2xsinπ/6)=2sin(2x+π/6)所以,y=2sin(2x+π/6)的最大值是2.