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Lebl-Basic-Analysis-I
· Problem 4.3.4
The Derivative
Mathematics · taylor-polynomial-bounds
Problem
Suppose
f
:
R
→
R
f : \mathbb{R} \to \mathbb{R}
f
:
R
→
R
has
n
n
n
continuous derivatives. Show that for every
x
0
∈
R
x_0 \in \mathbb{R}
x
0
∈
R
, there exist polynomials
P
P
P
and
Q
Q
Q
of degree
n
n
n
and an
ϵ
>
0
\epsilon > 0
ϵ
>
0
such that
P
(
x
)
≤
f
(
x
)
≤
Q
(
x
)
P(x) \leq f(x) \leq Q(x)
P
(
x
)
≤
f
(
x
)
≤
Q
(
x
)
for all
x
∈
[
x
0
,
x
0
+
ϵ
]
x \in [x_0, x_0 + \epsilon]
x
∈
[
x
0
,
x
0
+
ϵ
]
and
Q
(
x
)
−
P
(
x
)
=
λ
(
x
−
x
0
)
n
Q(x) - P(x) = \lambda(x - x_0)^n
Q
(
x
)
−
P
(
x
)
=
λ
(
x
−
x
0
)
n
for some
λ
≥
0
\lambda \geq 0
λ
≥
0
.
Related theory
Taylor S Theorem And Error Bounds
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