AKIN, Lutfi2019-05-242019-05-242018-01-192575-6028https://hdl.handle.net/20.500.12514/687Approximation theory has very important applications of polynomial approximation in various areas of functional analysis, Harmonic analysis, Fourier analysis, application mathematic, operator theory in the field generalized derivatives and numerical solutions of differential and integral equations, etc. Integral operators is very important in Harmonic and Fourier analysis. The study of approximation theory is a well-established area of research which deals with the problem of approximating a function f by means of a sequence n L of positive linear operators. Generalized derivatives (Riemann, Peano and Taylor derivative) are more general than ordinary derivative. Approximation theory is very important for mathematical world. Nowadays, many mathematicians are working in this field.eninfo:eu-repo/semantics/openAccessRiemann Derivative, Kernel Function, Diferantiable Function, Operator TheoryArticle