f(X)=(1-cos4x)/2+√3/2sin4x
=sin(4x-π/6)+1/2
解不等式π/2+2kπ≤4x-π/6≤3π/2+2kπ (k∈Z)
得 π/6+kπ/2≤x≤5π/12+kπ/2 (k∈Z)
单调减区间[π/6+kπ/2,5π/12+kπ/2] (k∈Z)