设函数f(x)=?1(x<0)x2?1(0≤x≤1)x+3(x>1)(1)求f(x)在x=0处的左右极限,并判断f(x)在x=0处是否

2025-01-30 14:02:21
推荐回答(1个)
回答1:

(1)∵
lim
x→0+
f(x)=
lim
x→0+
(x2?1)=?1

lim
x→0?
f(x)=
lim
x→0?
(?1)=?1

lim
x→0+
f(x)=
lim
x→0?
f(x)=?1

又f(0)=02-1=-1.
∴f(x)在x=0处有极限且连续.

(2)
lim
x→1+
f(x)=
lim
x→1+
(x+3)=4
lim
x→1?
f(x)=
lim
x→1?
(x2?1)=0

lim
x→1+
f(x)
lim
x→1?
f(x)
,即f(x)在x=1处极限不存在,也不连续;
   x=2在f(x)的连续区间(1,+∞)内,
故f(x)在x=2处是连续的.