Berrabah, FerialSupervisor:LAKEHALI, Belkacem2022-07-252022-07-252022-06-10http://dspace.univ-msila.dz:8080//xmlui/handle/123456789/30963The main objective of this work is to present a numerical method for finding approximate certain solutions of second-order ordinary differential equations. using Chebyshev Polynomials. Then, applying this method on some examples for comparing the results with exact solution and the obtainable results using other numerical methods to show the accuracy and the effectiveness of this method.enHilbert space, Linear ordinary differential equations, Chebyshev polynomials, approximation method.Thesis