2/3a+5-(3-1/3a)=a+2当a+2>0时,即a>-2时,2/3a+5>3-1/3a当a+2=0时,即a=-2时,2/3a+5=3-1/3a当a+2<0时,即a<-2时,2/3a+5<3-1/3a