設函數f(x)={x-1,x≥1,x,-1

設函數f(x)={x-1,x≥1,x,-1

(x→0)limf(x)=(x→0)limx=0
(x→1左)limf(x)=1、(x→1右)limf(x)=1-1=0,左極限不等右極限,極限不存在.
(x→2)limf(x)=(x→2)lim(x-1)=2-1=1