“…Delay differential equation is a branch of functional differential equation arising in several applications from various fields of studies, for instances biology, population dynamics, chemistry, physics, control theory, and many others [2,3,7,14,16,20,21,24,25]. Unlike in the case of ordinary differential equations (ODEs) the unknown functions in DDEs depend not only on the present values of derivatives of independent variables, but also depend on the values of the functions at some previous times.…”