设根号(a+1/2)=x 根号(b+1/2)=ya=x^2-1/2 b=y^2-1/2a+b=x^2+y^2-1=1x^2+y^2=2 2xy<=x^2+y^2=2x^2+y^2+2xy<=4(x+y)^2<=4 0根号(a+1/2)+根号(b+1/2)的范围是(0,2]
