y=-sin(2x-π/3)所以y和sin(2x-π/3)单调性相反所以y减区间即sin(2x-π/3)的增区间sinx的增区间是(2kπ-π/2,2kπ+π/2)所以2kπ-π/2<2x-π/3<2kπ+π/22kπ-π/6<2x<2kπ+5π/6kπ-π/12所以y的减区间是(kπ-π/12,kπ+5π/12)
