求y=sin(派/4-2x)的单调区间
1个回答

函数y=sin(π/4-2x)的单调递减区间

y=sin(π/4-2x)

=sin[-(2x-π/4)]

=-sin(2x-π/4)

要求y的单调递减区间,只需要求sin(2x-π/4)的单调递增区间即可

2kπ-π/2≤2x-π/4≤2kπ+π/2

kπ-π/8≤x≤kπ+3π/8 k∈z

同样要求y的单调递增区间,只需要求sin(2x-π/4)的单调递减区间即可

2kπ+π/2≤2x-π/4≤2kπ+3π/2

2kπ+π/4≤2x≤2kπ+7π/4

kπ+π/8≤x≤kπ+7π/8 k∈z

所以

函数y=sin(π/4-2x)的单调递减区间为[kπ-π/8,kπ+3π/8],k∈z

函数y=sin(π/4-2x)的单调递增区间为[kπ+π/8,kπ+7π/8],k∈z