Oscillations for a Class of Second Order Nonlinear Differential Equations

Abstract:

      In this paper, we disscuss a class of second order nonlinear differential equations (a(t)y′(t))′+p(t)y′(t-τ(t))-q(t)f(y(t))=0,　t≥t₀(1) and (a(t)y′(t))′-p(t)y′(t+τ(t))-q(t)f(y(t))=0,　t≥t₀(2) where, a(t),p(t),q(t),τ(t)∈C ［(t₀，∞),(0,∞)］,f(u)∈C(R,R)， sufficient conditions are obtained for all solutions of the equations to be oscillatory.