具正负系数的偶数阶中立型微分方程非振动解的存在性

Existence of Nonveoscillatory Solution of Even Order Linear Neutral Delay Equations

研究具正负系数的偶数阶中立型微分方程ｄｎ／ｄｔｎ［ｘ（ｔ）＋ｐｘ（ｔ－τ）］＋Ｑ１（ｔ）ｘ（ｔ－σ１）－Ｑ２（ｔ）ｘ（ｔ－ σ２）＝０，其中ｎ为偶数，获得了该方程非振动解存在的充分条件．

The neutral delay differential equation wiyh positive and negative coefficients Dn/dtn[x(t)+px(t-τ)]+Q1(t)x(t-σ1)-Q2(t)x(t- σ2)=0. wheren is even number,is studied,and a sufficient condition for the existen ee of a nonoscollatory solution of this equation is obtined.