exo7 1465

1

Soient \(a_{1}, \ldots, a_{n},b_{1}, \ldots, b_{n}, c_{1}, \ldots, c_{n}\) des réels positifs.
Montrer que \(\sum\limits_{k = 1}^{n}{a_{k}b_{k}c_{k}} \leq \sum\limits_{k = 1}^{n}{a_{k}^{2}c_{k}} \sum\limits_{k = 1}^{n}{b_{k}^{2}c_{k}}\).