## On stability and boundedness of solutions of a certain fourth-order delay differential equation.(English)Zbl 0697.34063

A Razumikhin-type theorem is used to obtain sufficient conditions for uniform asymptotic stability and boundedness of solutions of a fourth- order scalar delay-differential equation of the form $x^{''''}(t)+f(x''(t))x'''(t)+\alpha_ 2x''(t)+\beta_ 2x''(t- h)+g(x'(t-h))+\alpha_ 4x(t)+\beta_ 4x(t-h)=P(t).$ The proof utilizes a Lyapunov function obtained by J. O. C. Ezeilo in study of a related ordinary differential equation [J. Math. Anal. Appl. 5, 136- 146 (1962; Zbl 0107.296)].
Reviewer: L.I.Grimm

### MSC:

 34K99 Functional-differential equations (including equations with delayed, advanced or state-dependent argument) 34K20 Stability theory of functional-differential equations 34D20 Stability of solutions to ordinary differential equations 34C11 Growth and boundedness of solutions to ordinary differential equations

Zbl 0107.296
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