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2023 Tuymaada Olympiad
3
Inequality with cubic roots
Inequality with cubic roots
Source: Tuymaada 2023 Senior P3
July 7, 2023
algebra
Problem Statement
Prove that for every positive integer
n
≥
2
n \geq 2
n
≥
2
,
∑
1
≤
i
≤
n
i
n
+
1
3
n
≤
∑
1
≤
i
≤
n
−
1
i
n
3
n
−
1
.
\frac{\sum_{1\leq i \leq n} \sqrt[3]{\frac{i}{n+1}}}{n} \leq \frac{\sum_{1\leq i \leq n-1} \sqrt[3]{\frac{i}{n}}}{n-1}.
n
∑
1
≤
i
≤
n
3
n
+
1
i
≤
n
−
1
∑
1
≤
i
≤
n
−
1
3
n
i
.
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