A singular periodic Ambrosetti–Prodi problem of Rayleigh equations without coercivity conditions

In this paper, we use the Leray–Schauder degree theory to study the following singular periodic problems: [Formula: see text], [Formula: see text], where [Formula: see text] is a continuous function with [Formula: see text], function [Formula: see text] is continuous with an attractive singularity at the origin, and [Formula: see text] is a constant. We consider the case where the friction term [Formula: see text] satisfies a local superlinear growth condition but not necessarily of the Nagumo type, and function [Formula: see text] does not need to satisfy coercivity conditions. An Ambrosetti–Prodi type result is obtained.