Resumen de Oscillation of first order neutral differential equations with positive and negative coefficients

Jurang Yan, Wantong Li

• We obtain some new sharp sufficient conditions for the oscillation of all solutions of the first order neutral differential equation with positive and negative coefficients of the form $$\frac{d}{dt}\bigl(x(t) - R(t)x(t - r)\bigr)+ P(t)x(t - \tau ) - Q(t)x(t -\delta) = 0$$ where $P,Q,R\in C([t_0,\infty),R^^), r\in (0,\infty)$ and $\tau,\delta\in R^+$. In particular, the conditions are necessary and sufficient when the coefficients are constants. As corollaries, many known results are extended and improved in the literature.