*Article* **Asymptotic Properties of Neutral Differential Equations with Variable Coefficients**

#### **Omar Bazighifan 1,2,†, Rami Ahmad El-Nabulsi 3,\*,† and Osama Moaaz 4,†**


Received: 24 April 2020; Accepted: 10 August 2020; Published: 12 August 2020

**Abstract:** The aim of this work is to study oscillatory behavior of solutions for even-order neutral nonlinear differential equations. By using the Riccati substitution, a new oscillation conditions is obtained which insures that all solutions to the studied equation are oscillatory. The obtained results complement the well-known oscillation results present in the literature. Some example are illustrated to show the applicability of the obtained results.

**Keywords:** even-order differential equations; neutral delay; oscillation
