Solubility of a resultant equation and applications

Abstract

The large sieve is used to estimate the density of integral quadratic polynomials $Q$, such that there exists an odd degree integral polynomial which has resultant $\pm 1$ with $Q$. Given a monic integral polynomial $R$ of odd degree, this is used to show that for almost all integral quadratic polynomials $Q$, there exists a prime $p$ such that $Q$ and $R$ share a common root in the algebraic closure of the finite field with $p$ elements. Using recent work of Landesman, an application to the average size of the odd part of the class group of quadratic number fields is also given.

14 pages; this version corrects an error that was pointed out to the authors by Fabian Gundlach