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Rioplatense Mathematical Olympiad, Level 3
1995 Rioplatense Mathematical Olympiad, Level 3
4
1/b = sum 1/ n_k
1/b = sum 1/ n_k
Source: IV - Rioplatense 1995 L3 P4
September 19, 2022
number theory
Problem Statement
Given the natural numbers
a
a
a
and
b
b
b
, with
1
≤
a
<
b
1 \le a <b
1
≤
a
<
b
, prove that there exist natural numbers
n
1
<
n
2
<
.
.
.
<
n
k
n_1<n_2< ...<n_k
n
1
<
n
2
<
...
<
n
k
, with
k
≤
a
k \le a
k
≤
a
such that
a
b
=
1
n
1
+
1
n
2
+
.
.
.
+
1
n
k
\frac{a}{b}=\frac{1}{n_1}+\frac{1}{n_2}+...+\frac{1}{n_k}
b
a
=
n
1
1
+
n
2
1
+
...
+
n
k
1
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