Asymptotic behavior of solutions of neutral differential equations with positive and negative coefficients

Sufficient conditions are established for the asymptotic behavior of solutions of neutral differential equations with positive and negative coefficients x(t) − P(t)x(t − τ) +Q1(t)x(t − σ1) −Q2(t)x(t − σ2) = 0, t t0, where τ,σ1,σ2 ∈ (0,∞), P,Q1,Q2 ∈ C([t0,∞),R). Some known results are generalized and improved.  2003 Elsevier Science (USA). All rights reserved