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最小值为-2 x=0
请采纳。
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最小值为-2 x=0
请采纳。