函数y=2sin（3x+π4）-1的单调递减区间为．

Question

函数y=2sin（3x+(π)/(4)）-1的单调递减区间为______．

Answer 1

令2kπ+(π)/(2)≤3x+(π)/(4)≤2kπ+(3π)/(2)，k∈z，求得 (2kπ)/(3)+(π)/(12)≤x≤(2kπ)/(3)+(7π)/(36)，
故函数的减区间为 [(2kπ)/(3)+(π)/(12)，(2kπ)/(3)+(7π)/(36)]，k∈Z，
故答案为：[(2kπ)/(3)+(π)/(12)，(2kπ)/(3)+(7π)/(36)]，k∈z．