The Existence and Uniqueness of Periodic Solutions for Some Nonlinear n th-Order Differential Equations

Abstract

The nonlinear $n$th-order differential equations are considered. By using inequality techniques and coincidence degree theory, some criteria are obtained to guarantee the existence and uniqueness of $T$-periodic solutions for the equations. The obtained results are also valid and new for the problem discussed in the previous literature. Moreover, two illustrative examples are provided to illustrate the effectiveness of our results.