Question

函数y=5sin(pai/4-3x)的单调减区间是?

Answer 1

y=5sin(π/4-3x)= -5sin(3x-π/4) ,

由已知得 -π/2+2kπ ≤ 3x-π/4 ≤ π/2+2kπ ,

因此 -π/12+2kπ/3 ≤ x ≤ π/4+2kπ/3 ,

所以函数的单调减区间是 [ -π/12+2kπ/3,π/4+2kπ/3] ,k∈Z ,