Suppose that
is
continuous on
(
0
,
1
)
and that
lim
x
→
0
+
f
(
x
)
=
∞
show that
f
is not uniformly continuous
Suppose for the sake of contradiction that
f
is uniformly continuous and take
ϵ
=
1
therefore we obtain some
r
∈
R
+
such that for any
x
,
a
∈
S
if
|
x
−
a
|
<
r
implies that
|
f
(
x
)
−
f
(
a
)
|
<
ϵ
=
1
.
Note that this implies that for any
a
,
b
∈
(
0
,
r
)
we have
|
f
(
a
)
−
f
(
b
)
|
<
1
clearly this will lead to nonsense as it blows up around
0
and so we should be able to find two points whose vertical distance is greater or equal to
1
.
To do this let
x
∈
(
0
,
r
)
, since we know that
lim
x
→
0
+
f
(
x
)
=
∞
therefore by taking
δ
=
r
,
M
=
f
(
x
)
+
1
we obtain some
a
∈
(
0
,
r
)
such that
f
(
a
)
>
M
=
f
(
x
)
+
1
therefore we have that
f
(
a
)
−
f
(
x
)
>
1
which implies that
1
>
|
f
(
a
)
−
f
(
x
)
|
=
|
f
(
x
)
−
f
(
a
)
|
which is a contradiction, so that
f
is uniformly continuous.