Oscillation Criteria for Delay Differential Equations with Positive and Negative Coefficients

Consider the delay differential equation with positive and negative coefficients x'(t)+ 1 tlnt i = 1 Σp i x(t α)i 1 tlnt i = 1 Σq i x(t β)i =0,where0α i 1,0β i 1,p i 0andq i ≥0 are constants.It is proved that a sufficient condition of oscillation of all solutions of the equation isα i β i,n Σp i n Σq i,n Σq i ln β i α ≤1,n Σ(pi-q)iln 1 α 1 e whereα=max{α 1,α 2,…,α n ≤ Σ}.