lim (x-4)/[√(x-3)-1]x→4=lim (x-4)[√(x-3)+1] / [√(x-3)-1][√(x-3)+1]x→4=lim (x-4)[√(x-3)+1] / (x-3-1) (以上两步是分母有理化)x→4=lim (x-4)[√(x-3)+1] / (x-4)x→4=lim [√(x-3)+1] (分子、分母的x-4约分掉了)x→4=√(4-3)+1=1+1=2
