y=2sin(-2x+π/3) 和y=3cos(2/3x+π/4)单调区间
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y=2sin(-2x+π/3)

单调递增区间:

由:-π/2+2kπ≤-2x+π/3≤π/2+2kπ

得:-π/12-kπ≤x≤5/12π-kπ,k∈Z

即:[-π/12-kπ,5/12π-kπ]

单调递减区间:

由:π/2+2kπ≤-2x+π/3≤3π/2+2kπ

得:-7/12π-kπ≤x≤-π/12-kπ,k∈Z

即:[-7/12π-kπ,-π/12-kπ]

y=3cos(2/3x+π/4)

单调递增区间:

由:-π+2kπ≤2/3x+π/4≤2kπ

得:-15/8π+3kπ≤x≤3kπ-3π/8,k∈Z

即:[-15/8π+3kπ,3kπ-3π/8]

单调递减区间:

由:2kπ≤2/3x+π/4≤π+2kπ

得:3kπ-3/8π≤x≤9/8π+3kπ,k∈Z

即:[3kπ-3/8π,9/8π+3kπ]