where A(t), B(t), C(t) Î C[0,1], f(t, u) : [0,1] × [0, ∞) ® [0. ∞) is continuous. In recent years, BVPs for sixth-order ordinary differential equations have been studied extensively, see [1-7] and the references therein. For example, Tersian and Chaparova [1] have studied the existence of positive solutions for the following systems (1.2): { u(6) + Au(4) + Bu′′ + Cu − f (t, u) = 0. 0 < x < L, u...