Asymptotic behavior of nonoscillatory solutions to nn-th order nonlinear neutral differential equations

For a class of nn-th order nonlinear neutral differential equations, sufficient conditions for all nonoscillatory solutions to satisfy limt→+∞t1−nx(t)=alimt→+∞t1−nx(t)=a are established. For another class of equations, necessary and sufficient conditions for nonoscillatory solutions to satisfy the above condition are obtained. Our theorems complement and extend recent results reported in the literature.