Odredite najveću konstantu
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takvu da, za sve prirodne
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i realne
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vrijedi:
.
Determine the largest constant
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such that for all natural numbers
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and real numbers

, the following inequality holds:
.
[lang=hr]
Odredite najveću konstantu $S$ takvu da, za sve prirodne $n$ i realne $a_1 \dots a_n$ vrijedi:
$$\sum_{i=1}^{n}\sum_{j=1}^{n}(n-|i-j|)x_ix_j \geq S\sum_{j=1}^{n}x^2_i$$.
[/lang]
[lang=en]
Determine the largest constant $S$ such that for all natural numbers $n$ and real numbers $a_1 \dots a_n$, the following inequality holds:
$$\sum_{i=1}^{n}\sum_{j=1}^{n}(n-|i-j|)x_ix_j \geq S\sum_{j=1}^{n}x^2_i$$.
[/lang]