Further Results on the Instability of Solutions of Certain Nonlinear Vector Differential Equations of Fifth Order

Abstract

By using Lyapunov's second method [13], some new results are established, which insure that the zero solution of non-linear vector differential equations of the form X((5)) + Psi((X) over dot, (X) doubt over dot) (X)triple over dot> + Phi(X, (X) over dot, (X) doubtle over dotm (X) triple over dot, X((4))) + Theta((X) over dot) + F(X) = 0 is unstable.