f*x(=1/2*sin4x-√3(1-cos4x)/2=sin4xcosπ/3+cos4xsinπ/3-√3/2=sin(4x+π/3)-√3/2π/3<=4x+π/3<=4π/3所以-√3/2<=sin(4x+π/3)<=1在减去-√3/2值域[-√3,1-√3/2]
