设f(x)=limn→∞(n−1)xnx2+1,则f(x)的间断点为x=_.

问题描述:

f(x)=

lim
n→∞
(n−1)x
nx2+1
,则f(x)的间断点为x=______.

解; 显然,当x=0时,f(x)=0;
当x≠0时,f(x)=

lim
n→∞
(n−1)x
nx2+1
=x
lim
n→∞
1−
1
n
x2+
1
n
=x•
1
x2
1
x

f(x)=
0 ,x=0
1
x
,x≠0

lim
x→0
f(x)=∞

从而x=0是f(x)的间断点.