Best approximation for fractional derivative of functions in Lp,α(X)

In this paper algebraic polynomials approximation in the space Lp,α(X) considered and it is concerned mainly with algebraic polynomial approximation of unbounded function in weighted space in terms convolution f ∗ g, With f and g belongs in weighted space . In addition, We obtain estimate for fractional derivatives order of functions in Lp,α(X).