y=2sin（2x－派/3）y=2sin(2x-π/3)y'=4cos(2x-π/3)令y'=0,即：4cos(2x-π/3)=0整理,有：cos(2x-π/3)=0解得：x=kπ/2+5π/12,k=0、±1、±2、±3、……楼主所给的函数,有无数条对称轴.对称轴的通式是：x=kπ/2+5π...