Global attractivity of solutions of nonlinear delay differential equations with a forcing term

In this paper, we give sufficient conditions for every solution of the delay differential equation x′(t)=−p(t)f(x(t−τ))+r(t),x′(t)=−p(t)f(x(t−τ))+r(t), to converge to zero. Our results extend and improve several known results in the literature. An application of our main results to an equation derived from mathematical biology is also given.