Volume 30 • Number 1 • 2007   • About Uniform Boundedness and Convergence of Solutions of Certain Non-Linear Differential Equations of Fifth-Order Cemil Tunc Abstract. In this paper, we establish sufficient conditions under which all solutions of equation of the type x(5)+ f(t,x',x'',x''',x(4)) + f (t, x', x'', x''')+ y (t,x, x', x'')+ g(t,x, x')+ e(t)h(x) = p(t,x,x', x'', x''',x(4)) are uniformly bounded and tend to zero as t tend to ∞. Our theorem is stated in a more general form; it extends some related results known in the literature. Also, the relevance of our result is to show that the results established in Abou El-Ela and Sadek [2,3] and Sadek [13] contain some superfluous conditions. 2000 Mathematics Subject Classification: 34D05. Full text: PDF