2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/139876If c is a positive number, Descartes' rule of signs implies that multiplying a polynomial f(x) by c - x introduces an odd number of changes of sign in the coefficients. We turn this around, proving this fact about sign changes inductively and deriving Descartes' rule from it.3 pagesGeneral Mathematics26Ctext