f（x）=-sin2x-cos2x+3sin2x-cos2x=2sin2x-2cos2x=2根号2sin(2x-π/4)T=2π/2=π-π/2+2kπ≤2x-π/4≤π/2+2kπ k属于Z-π/8+kπ≤x≤3π/8+kπ递增区间[-π/8+kπ,3π/8+kπ]在0-π/2上最大值为2根号2,x=3π/8最小...