Ayinla, Ally YeketiOgunniran, Muhyideen O.Odetunde, Opeyemi2023-05-092023-05-092017-09Ayinla A.Y., Ogunniran M.O. and Odetunde O.https://uilspace.unilorin.edu.ng/handle/20.500.12484/9808This work deals with integrated collocation approximation methods for solving high order ordinary differential equations by Chebyshev polynomials and power series bases functions. The assumed approximate solution in terms of Chebyshev polynomials and power series are substituted into the general high order ordinary differential equations considered. Thus, after simplification, the resulting equation is then collocated for both cases and thus resulted into algebraic linear system of equations which are then solved by Mathematica 5.2 to obtain the unknown constants involved in the approximate solution. The methods are illustrated on three examples. The results obtained in terms of absolute errors are tabulated for comparison. From the tables of results, we observed that Chebyshev polynomials approximation gives better result for all cases of N (i.e. the degree of approximant) in the work.enIntegrated CollocationChebyshev PolynomialPower SeriesArticle