y=sin(π/4—2X )=-sin(2x-π/4)的单调增区间即
为sin(2x-π/4)的单调减区间,
由π/2+2kπ≤2x-π/4≤3π/2+2kπ
3π/4+2kπ≤2x≤7π/4+2kπ
3π/8+kπ≤x≤7π/8+kπ,
即y=sin(π/4—2X )单调增区间为[3π/8+kπ,7π/8+kπ].