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2021 Romania National Olympiad
1
Romania National Olympiad Grade 11 P1
Romania National Olympiad Grade 11 P1
Source:
April 28, 2021
real analysis
Problem Statement
Let
f
:
[
a
,
b
]
→
R
f:[a,b] \rightarrow \mathbb{R}
f
:
[
a
,
b
]
→
R
a function with Intermediate Value property such that
f
(
a
)
∗
f
(
b
)
<
0
f(a) * f(b) < 0
f
(
a
)
∗
f
(
b
)
<
0
. Show that there exist
α
\alpha
α
,
β
\beta
β
such that
a
<
α
<
β
<
b
a < \alpha < \beta < b
a
<
α
<
β
<
b
and
f
(
α
)
+
f
(
β
)
=
f
(
α
)
∗
f
(
β
)
f(\alpha) + f(\beta) = f(\alpha) * f(\beta)
f
(
α
)
+
f
(
β
)
=
f
(
α
)
∗
f
(
β
)
.
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