Tusi Mathematical Research Group (TMRG) and Department of Pure Mathematics, Ferdowsi University of Mashhad (in cooperation with
The Center of Excellence in Analysis on Algebraic Structures)Khayyam Journal of Mathematics2423-47883120170101Periodic Solutions for Third-Order Nonlinear Delay Differential Equations with Variable Coefficients12214449310.22034/kjm.2017.44493ENAbdelouaheb ArdjouniDepartment of Mathematics and Informatics, University of Souk Ahras, P.O.
Box 1553, Souk Ahras, 41000, Algeria.Farid NouiouaDepartment of Mathematics and Informatics, University of Souk Ahras, P.O.
Box 1553, Souk Ahras, 41000, Algeria.Ahcene DjoudiDepartment of Mathematics, University of Annaba, P.O. Box 12, Annaba,
23000, Algeria.Journal Article20161116In this paper, the following third-order nonlinear delay differential equationwith periodic coefficients%begin{align*}& x^{primeprimeprime}(t)+p(t)x^{primeprime}(t)+q(t)x^{prime}(t)+r(t)x(t)\& =fleft( t,xleft( tright) ,x(t-tau(t))right) +frac{d}{dt}gleft(t,xleft( t-tauleft( tright) right) right) ,end{align*}is considered. By employing Green's function, Krasnoselskii's fixed pointtheorem and the contraction mapping principle, we state and prove theexistence and uniqueness of periodic solutions to the third-order nonlineardelay differential equation.http://www.kjm-math.org/article_44493_fca28ec0388a064bcfebffd47c16b12f.pdf