T=2π/k 1<2π/k<32π/3K最小=3则y=3sin(3x+π/3)增区间2kπ-π/2<=3X+π/3<=2Kπ+π/2,即【2Kπ/3-5π/18,2Kπ/3+π/18】减区间2kπ+π/2<=3X+π/3<=2Kπ+3π/2,
解;1<2π/k<3, 于是得 2π/3当k=3时, y=3sin(3x+π/3) 单增区间:2kπ/3-5π/18≤x≤2kπ/3+π/18, 单减区间 2kπ/3+π/18≤x≤2kπ/3+7π/18