Hudde's rules


In mathematics, Hudde's rules are two properties of polynomial roots described by Johann Hudde.
1. If r is a double root of the polynomial equation
2. If for x = a the polynomial
Hudde was working with Frans van Schooten on a Latin edition of La Géométrie of René Descartes. In the 1659 edition of the translation, Hudde contributed two letters: "Epistola prima de Redvctione Ǣqvationvm", and "Epistola secvnda de Maximus et Minimus". These letters may be read by the Internet Archive link below.