f(x)=2sinxcosx+2cos平方x-1
=sin2x+cos2x
=√2(sin2xcosπ/4+cos2xsinπ/4)
=√2sin(2x+π/4)
所以最小正周期T=2π/2=π
增：〔kπ-3π/8,kπ+π/8〕
减：[kπ+π/8,kπ+5π/8]