Forced oscillation of n(th)-order nonlinear differential equations

Some new oscillation criteria for forced nonlinear equations of the form x((n)) (t) - q(t)/x(t)/(lambda) sgn x(t) = f(t), lambda > 1, are established. We impose no restriction on the forcing term f(t) as those assumed in [1,2]. We further employ the technique presented here to establ ish new oscillation criteria for forced nonlinear neutral equations of the form (x(t)+ cx [t - tau])((n)) + a(t)x(t) + b(t)x [t - tau] = f(t) + q(t)/x(t)/( lambda)sgn x(t) + p(t) /x[t - tau]/(sigma)sgn x[t - tau], where lambda > 1 and sigma > 1. (C) 2000 Elsevier Science Ltd. All rights reserved.