MathDB
Intervals Without Any "Quadratic" Numbers

Source: Turkey JBMO TST 2015 P5

June 23, 2016
algebra

Problem Statement

A quadratic number is a real root of the equations ax2+bx+c=0ax^2 + bx + c = 0 where a,b,c{1,2,,10}|a|,|b|,|c|\in\{1,2,\ldots,10\}. Find the smallest positive integer nn for which at least one of the intervals\left(n-\dfrac{1}{3}, n\right)  \text{and} \left(n, n+\dfrac{1}{3}\right)does not contain any quadratic number.