For all n polynomial value P(n) shall be positive
Source: IMO Longlist 1989, Problem 12
September 18, 2008
algebrapolynomialinequalitiesalgebra unsolved
Problem Statement
Let be a polynomial such that the following inequalities are satisfied:
P(2) > 2P(1) \minus{} P(0); P(3) > 3P(2) \minus{} 3P(1) \plus{} P(0);
and also for every natural number P(n\plus{}4) > 4P(n\plus{}3) \minus{} 6P(n\plus{}2)\plus{}4P(n \plus{} 1) \minus{} P(n).
Prove that for every positive natural number is positive.