Abstract: In this paper we investigate the asymptotic properties of all solutions of the delay differential equation $$y'(x)=a(x)y(\tau (x))+b(x)y(x),\qquad x\in I=[x_0,\infty ).$$ We set up conditions under which every solution of this equation can be represented in terms of a solution of the differential equation $$z'(x)=b(x)z(x),\qquad x\in I$$ and a solution of the functional equation $$|a(x)|\varphi (\tau (x))=|b(x)|\varphi (x),\qquad x\in I.$$
Keywords: asymptotic behaviour, differential equation, delayed argument, functional equation
Classification (MSC2000): 34K15, 34K25, 39B99
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