MathDB
Writing functions on a board

Source: St Petersburg 2021 11.4

December 23, 2021
functionalgebra

Problem Statement

The following functions are written on the board, F(x)=x2+12x2,G(x)=sin(πx2),H(x)=1.F(x) = x^2 + \frac{12}{x^2}, G(x) = \sin(\pi x^2), H(x) = 1. If functions f,gf,g are currently on the board, we may write on the board the functions f(x)+g(x),f(x)g(x),f(x)g(x),cf(x)f(x) + g(x), f(x) - g(x), f(x)g(x), cf(x) (the last for any real number cc). Can a function h(x)h(x) appear on the board such that h(x)x<13|h(x) - x| < \frac{1}{3} for all x[1,10]x \in [1,10] ?