y=sin2x+cos2x
=√2(sin2x*√2/2+cos2x*√2/2)
=√2sin(2x+π/4)
最小正周期T=2π/w=2π/2=π
∵-1≤sin(2x+π/4)≤1
∴-√2≤√2sin(2x+π/4)≤√2
最大值为√2
最小值为-√2
令-π/2+2kπ≤2x+π/4≤π/2+2kπ
-3π/4+2kπ≤2x≤π/4+2kπ
-3π/8+kπ≤x≤π/8+2kπ
所以单调递增区间为{x l -3π/8+kπ≤x≤π/8+2kπ}(k∈Z)
令π/2+2kπ≤2x+π/4≤3π/2+2kπ
π/4+2kπ≤2x≤5π/4+2kπ
π/8+kπ≤x≤5π/8+2kπ
所以单调递减区间为{x l π/8+kπ≤x≤5π/8+2kπ}(k∈Z)