y=sin2x-根号3·cos2x
= 2(sin2x cosπ/3 - cos2x sinπ/3)
= 2sin(2x-π/3)
当2x-π/3∈【2kπ,2kπ+π),即x∈【kπ+π/6,kπ+2π/3),其中k∈Z时,单调递增