MathDB
Problems
Contests
International Contests
Baltic Way
2009 Baltic Way
2
Inequality
Inequality
Source: Baltic way 2009
November 11, 2009
inequalities
algebra
polynomial
inequalities proposed
Problem Statement
Let
a
1
,
a
2
,
…
,
a
100
a_1,a_{2},\ldots ,a_{100}
a
1
,
a
2
,
…
,
a
100
be nonnegative integers satisfying the inequality
a
1
⋅
(
a
1
−
1
)
⋅
…
⋅
(
a
1
−
20
)
+
a
2
⋅
(
a
2
−
1
)
⋅
…
⋅
(
a
2
−
20
)
+
…
+
a
100
⋅
(
a
100
−
1
)
⋅
…
⋅
(
a
100
−
20
)
≤
100
⋅
99
⋅
98
⋅
…
⋅
79.
a_1\cdot (a_1-1)\cdot\ldots\cdot (a_1-20)+a_2\cdot (a_2-1)\cdot\ldots\cdot (a_2-20)+\\ \ldots+a_{100}\cdot (a_{100}-1)\cdot\ldots\cdot (a_{100}-20)\le 100\cdot 99\cdot 98\cdot\ldots\cdot 79.
a
1
⋅
(
a
1
−
1
)
⋅
…
⋅
(
a
1
−
20
)
+
a
2
⋅
(
a
2
−
1
)
⋅
…
⋅
(
a
2
−
20
)
+
…
+
a
100
⋅
(
a
100
−
1
)
⋅
…
⋅
(
a
100
−
20
)
≤
100
⋅
99
⋅
98
⋅
…
⋅
79.
Prove that
a
1
+
a
2
+
…
+
a
100
≤
9900
a_1+a_2+\ldots+a_{100}\le 9900
a
1
+
a
2
+
…
+
a
100
≤
9900
.
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