Vrijeme: 09:15

Nejednakosti puštene s lanca | Inequalities unleashed from the chain #4

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.

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.