Putnam 1991 A3 and follow-up
Source: Curiosity
October 20, 2008
Putnamalgebrapolynomialcollege contests
Problem Statement
Find all real polynomials of degree for which there exist real numbers such that
(i) p(r_i) \equal{} 0, 1 \le i \le n, and
(ii) p' \left( \frac {r_i \plus{} r_{i \plus{} 1}}{2} \right) \equal{} 0, 1 \le i \le n \minus{} 1.
Follow-up: In terms of , what is the maximum value of for which consecutive real roots of a polynomial of degree can have this property? (By "consecutive" I mean we order the real roots of and ignore the complex roots.) In particular, is k \equal{} n \minus{} 1 possible for ?