Abstract
This paper is concerned with the distribution of zeros of all solutions of the first-order neutral differential equation
[x(t) + p(t)x(t - tau)]' + Q(t)x(t - sigma) = 0, t >= t(0),
where
p is an element of C([t(0), infinity), [0, infinity)), Q is an element of C([t(0), infinity), (0, infinity)) and tau, sigma is an element of R+.
New estimations for the distance between adjacent zeros of this neutral equation are obtained via comparison with a corresponding differential inequality. These results extend some known results from the non-neutral to the neutral case and improve other published results as well. (C) 2015 Elsevier Inc. All rights reserved.