Electronic Journal of Differential Equations, Vol. 2009(2009), No. 94, pp. 1-13. Title: Existence of solutions for second-order differential equations and systems on infinite intervals Authors: Toufik Moussaoui (E.N.S., Algiers, Algeria) Radu Precup (Babes-Bolyai Univ., Cluj, Romania) Abstract: We study the existence of nontrivial solutions to the boundary-value problem $$\displaylines{ -u''+cu'+\lambda u = f(x,u),\quad -\infty