y'=4cos（2x-π/3）≥0,则2kπ-π/2≤2x-π/3≤2kπ+π/2,k∈Z 2kπ-π/6≤2x≤2kπ+5π/6,kπ-π/12≤x≤kπ+5π/12,x∈【kπ-π/12,kπ+5π/12】k∈Z