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IMO Longlists
1987 IMO Longlists
75
IMO LongList 1987 - Inequality on 1987 positive reals
IMO LongList 1987 - Inequality on 1987 positive reals
Source:
September 6, 2010
inequalities
inequalities unsolved
Problem Statement
Let
a
k
a_k
a
k
be positive numbers such that
a
1
≥
1
a_1 \geq 1
a
1
≥
1
and
a
k
+
1
−
a
k
≥
1
(
k
=
1
,
2
,
.
.
.
)
a_{k+1} -a_k \geq 1 \ (k = 1, 2, . . . )
a
k
+
1
−
a
k
≥
1
(
k
=
1
,
2
,
...
)
. Prove that for every
n
∈
N
,
n \in \mathbb N,
n
∈
N
,
∑
k
=
1
1987
1
a
k
+
1
a
k
1987
<
1987
\sum_{k=1}^{1987}\frac{1}{a_{k+1} \sqrt[1987]{a_k}} <1987
k
=
1
∑
1987
a
k
+
1
1987
a
k
1
<
1987
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