“…where ρ, P 0 , h, E, L are constants, which extends the classical D'Alembert's wave equation, by considering the effects of the changes in the length of the strings during the vibrations. In recent years, problems involving Kirchhoff type operators have been studied in many papers, we refer to [14][15][16][17][18][19][20][21], in which the authors have used a variational method and topological method to get the existence of solutions. In this paper, motivated by the ideas introduced in [22] and the properties of Kirchhoff type operators in [22], we study the existence of positive solutions for system (2) by using the sub-and super solutions techniques.…”