content_image/326460.jpg content_image/326458.jpg content_image/326459.jpg
So, y ( t ) is continuous at the impulse points. 

Now, let y ( t ) be an eventually positive solution of inequality (6). Then y ( t ) > 0 , y ( t − τ ) > 0 , and y ([ t − 1]) > 0 for t > T. We will show that x ( t ) is an eventually positive solution of inequality (3). From (8), (9), and (6) we obtain that x ′ ( t ) + a ( t ) x ( t ) + b ( t ) x ( t − τ ) + c ( t ) x ([ t − 1]) 

Moreover, 

and 

<img src='content_image/326460.jpg'>

<img src='content_image/326458.jpg'>

<img src='content_image/326459.jpg'>

So, x ( t ) is an eventually positive solution of inequality (3). The proof is complete. Following we give several sufficient conditions for the oscillation of equation (1)-(2). 

Theorem 2. If one of the following conditions is satisfied then every solution of equation (1)-(2) is oscillatory: 

## 6 

