Problem A. 439. (November 2007)
A. 439. Prove that
Deadline expired on December 17, 2007.
Solution. Define also a0=1, and let , , and . We have to prove .
Applying the Cauchy-Schwarz inequailty on the sequences and ,
6 students sent a solution. 5 points: Lovász László Miklós, Tomon István, Wolosz János. 3 points: 1 student. 0 point: 1 student. Unfair, not evaluated: 1 solution.