Let f (x) = {X-1, X ≥ 1, x, - 1

Let f (x) = {X-1, X ≥ 1, x, - 1

( x→0) limf(x)=( x→0) limx=0
(x → 1 left) limf (x) = 1, (x → 1 right) limf (x) = 1-1 = 0, the left limit is unequal to the right limit, and the limit does not exist
(x→2)limf(x)=(x→2)lim(x-1)=2-1=1