IMC 2006 · Problem 6

Day 120 points13th IMC · Odessa, Ukraine

Statement

Find all sequences a0,a1,,ana_0, a_1, \dots, a_n of real numbers where n1n \ge 1 and an0a_n \ne 0, for which the following statement is true:

If f:RRf : \mathbb{R} \to \mathbb{R} is an nn times differentiable function and x0<x1<<xnx_0 < x_1 < \dots < x_n are real numbers such that f(x0)=f(x1)==f(xn)=0f(x_0) = f(x_1) = \dots = f(x_n) = 0 then there exists an h(x0,xn)h \in (x_0, x_n) for which

a0f(h)+a1f(h)++anf(n)(h)=0.a_0 f(h) + a_1 f'(h) + \dots + a_n f^{(n)}(h) = 0.

Official solution

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