Abstract
This paper concerns the oscillation of solutions of the differential eq.
[r(t) psi(x (t)) f (x(t))] + q (t) phi(g (x (t)), r (t)psi(x (t)) f (x(t))) = 0,
where u phi(u; v) > 0 for all u not equal 0; xg (x) > 0; x f (x) > 0 for all x not equal 0; psi(x) > 0 for all x is an element of R; r (t) > 0 for t >= t(0) > 0 and q is of arbitrary sign. Our results complement the results in [A. G. Kartsatos, On oscillation of nonlinear equations of second order, J. Math. Anal. Appl. 24 (1968), 665-668], and improve a number of existing oscillation criteria. Our main results are illustrated with examples.