versión ISSN 0716-0917
TUNC, Cemil. On the instability of solutions of an eighth order nonlinear differential equation of retarded type. Proyecciones (Antofagasta) [online]. 2011, vol.30, n.1, pp. 43-50. ISSN 0716-0917. doi: 10.4067/S0716-09172011000100004.
In this paper, we give some sufficient conditions on the instability of the zero solution of a kind of eighth order nonlinear differential equations of retarded type by using the Lyapunov direct method. The obtained sufficient conditions improve an existing result in the literature.
Palabras clave : Instability; the Lyapunov direct method; delay differential equation; eighth order.