MathDB
Math Prize 2022 Problem 5

Source:

October 12, 2022

Problem Statement

Given a real number aa, the floor of aa, written a\lfloor a \rfloor, is the greatest integer less than or equal to aa. For how many real numbers xx such that 1x201 \le x \le 20 is x2+2x=x2+2x? x^2 + \lfloor 2x \rfloor = \lfloor x^2 \rfloor + 2x \, ?