2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/99541The classical Jackson-Stechkin inequality estimates the value of the best uniform approximation of a periodic function by trigonometric polynomials of degree $\le n-1$ in terms of its $r$-th modulus of smoothness $ω_r(f,δ)$. The main result of the paper is in establishing the correct order of Jackson--Stechkin constants.20 pagesClassical Analysis and ODEs41A17; 41A44; 42A10text