MathDB
Putnam 2004 B1

Source:

December 11, 2004
Putnamalgebrapolynomialnumber theoryrelatively primeRational Root Theoremcollege contests

Problem Statement

Let P(x)=cnxn+cn1xn1++c0P(x)=c_nx^n+c_{n-1}x^{n-1}+\cdots+c_0 be a polynomial with integer coefficients. Suppose that rr is a rational number such that P(r)=0P(r)=0. Show that the nn numbers cnr,cnr2+cn1r,cnr3+cn1r2+cn1r,,cnrn+cn1rn1++c1rc_nr, c_nr^2+c_{n-1}r, c_nr^3+c_{n-1}r^2+c_{n-1}r, \dots, c_nr^n+c_{n-1}r^{n-1}+\cdots+c_1r are all integers.