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判断单调性 y=sin(x-π/6) y=sin(-2x+π/3)

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判断单调性 y=sin(x-π/6) y=sin(-2x+π/3)
判断单调性 y=sin(x-π/6) y=sin(-2x+π/3)
对于y=sinx:
其单调减区间是:x∈(2kπ+π/2,2kπ+3π/2);单调增区间是:x∈(2kπ+3π/2,2kπ+5π/2).
其中:k=0、±1、±2、±3……,下同.
即:单调增区间:2kπ+π/2<x<2kπ+3π/2,
单调减区间:2kπ+3π/2<x<2kπ+5π/2.
1、对于y=sin(x-π/6),有:
单调增区间:2kπ+π/2<x-π/6<2kπ+3π/2;单调减区间:2kπ+3π/2<x-π/6<2kπ+5π/2.
整理:单调增区间:2kπ+2π/3<x<2kπ+5π/3;单调减区间:2kπ+5π/3<x<2kπ+8π/3.
即:单调减区间是x∈(2kπ+2π/3,2kπ+5π/3);单调增区间是:x∈(2kπ+5π/3,2kπ+8π/3).
2、对于y=sin(-2x+π/3),有:
单调增区间:2kπ+π/2<-2x+π/3<2kπ+3π/2;单调减区间:2kπ+3π/2<-2x+π/3<2kπ+5π/2.
整理:单调增区间:-kπ-7π/12<x<-kπ-π/12;单调减区间:-kπ-13π/12<x<-kπ-7π/12.
即:单调减区间是x∈(-kπ-7π/12,-kπ-π/12);单调增区间是:x∈(-kπ-13π/12,-kπ-7π/12).