f(x)=2√3sinxcosx+2cos²x-1=√3sin(2x)+cos(2x)=2[(√3/2)sin(2x)+(1/2)cos(2x)]=2sin(2x+π/6)最小正周期T=2π/2=π当sin(2x+π/6)=1时，f(x)有最大值f(x)max=2；当sin(2x+π/6)=-1时，f(x)有最小值f(x)min=-2
