A global positive solution of a delay differential equation with indefinite coefficients

In this note, we show the existence of a global positive solution for a class of first-order delay differential equations: x ′ ( t ) + a 1 ( t ) x ( t ) + a 2 ( t ) x ( t − h ( t ) ) = 0 . In this study, we allow a 1 and a 2 to be of oscillating nature.