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Mathematics
Mathematics
Problem
A function
f
f
f
on
R
R
R
into itself is continuous at a point
a
a
a
in
R
R
R
, iff for each
ϵ
>
0
\epsilon > 0
ϵ
>
0
, there exists,
δ
>
0
\delta > 0
δ
>
0
such that (a)
∣
f
(
x
)
−
f
(
a
)
∣
<
ϵ
⇒
∣
x
−
a
∣
<
δ
|f(x) - f(a)| < \epsilon \Rightarrow |x - a| < \delta
∣
f
(
x
)
−
f
(
a
)
∣
<
ϵ
⇒
∣
x
−
a
∣
<
δ
(b)
∣
f
(
x
)
−
f
(
a
)
∣
>
ϵ
⇒
∣
x
−
a
∣
>
δ
|f(x) - f(a)| > \epsilon \Rightarrow |x - a| > \delta
∣
f
(
x
)
−
f
(
a
)
∣
>
ϵ
⇒
∣
x
−
a
∣
>
δ
(c)
∣
x
−
a
∣
>
δ
⇒
∣
f
(
x
)
−
f
(
a
)
∣
>
ϵ
|x - a| > \delta \Rightarrow |f(x) - f(a)| > \epsilon
∣
x
−
a
∣
>
δ
⇒
∣
f
(
x
)
−
f
(
a
)
∣
>
ϵ
(d)
∣
x
−
a
∣
<
δ
⇒
∣
f
(
x
)
−
f
(
a
)
∣
<
ϵ
|x - a| < \delta \Rightarrow |f(x) - f(a)| < \epsilon
∣
x
−
a
∣
<
δ
⇒
∣
f
(
x
)
−
f
(
a
)
∣
<
ϵ
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