f(x)=2cos^2x+2根号3sinxcosx-1
=cos(2x)+√3sin(2x)
=2*[1/2cos(2x)+√3/2sin(2x)]
=2sin(2x+π/6)
2kπ-π/2≤2x+π/6≤2kπ+π/2
kπ-π/3≤x≤kπ+π/6
单增区间：[kπ-π/3,kπ+π/6]
由y=sinx向左平移π/12,横坐标缩小1倍,纵坐标扩大1倍得到