函数y=sin(−2x+π6)的单调递减区间是(  ) A.[−π6+2kπ,π3+2kπ] k∈Z B.[π6+2kπ,5π6+2kπ] k∈Z C.[−π6+kπ,π3+kπ] k∈Z D.[π6+kπ,5π6+kπ] k∈Z

问题描述:

函数y=sin(−2x+

π
6
)的单调递减区间是(  )
A. [−
π
6
+2kπ,
π
3
+2kπ]
 k∈Z

B. [
π
6
+2kπ,
6
+2kπ]
 k∈Z

C. [−
π
6
+kπ,
π
3
+kπ]
 k∈Z

D. [
π
6
+kπ,
6
+kπ]
 k∈Z

y=sin(−2x+

π
6
)=-sin(2x-
π
6

π
2
+2kπ≤2x−
π
6
π
2
+2kπ

π
6
+kπ≤x≤
π
3
+kπ

∴函数y=sin(−2x+
π
6
)
的单调递减区间[−
π
6
+kπ,
π
3
+kπ]
,k∈Z
故选C.