Abstract
Suppose thatx(t) ∈ C (n)][a,b and has n zeros at the pointsa and b. It is shown that if x(n)(t) preserves sign on [a, b], then
where p and q are the multiplicities of the zeros of x(t) ata and b, respectively, and po=min{p,q}. Two-sided estimates of the Green's function for a two-point interpolation problem for the operator Lx ≡ x(n) are established in the proof. As an application, new conditions for the solvability of de la Vallée Poussin's two-point boundary problems are obtained.
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Translated from Matematicheskie Zametki, Vol. 21, No. 5, pp. 653–664, May, 1977.
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Pokornyi, Y.V. Some estimates of differentiable functions. Mathematical Notes of the Academy of Sciences of the USSR 21, 366–373 (1977). https://doi.org/10.1007/BF01788233
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DOI: https://doi.org/10.1007/BF01788233