f(x)=2cos^2x+√3sin2x+m
=√3sin2x+cos2x+m+1
=2sin(2x+π/6)+m+1
(1) 最小值周期T=2π/2=π
画图可知在【0,π】上单调递增区间为【0,π/6】,【2π/3,π】
（2）
x属于[0,π/6]
2x+π/6属于[π/6,π/2]
2sin(2x+π/6)属于[1,2]
f(x)属于[2+m,3+m]
2+m>-4 m>-6
3+m