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Fractional Parts of Square Roots, Continued

Source: Ukrainian Mathematical Olympiad 2023. Day 1, Problem 9.4

April 5, 2023
algebrafractional part

Problem Statement

Find the smallest real number CC, such that for any positive integers xyx \neq y holds the following:
min({x2+2y},{y2+2x})<C\min(\{\sqrt{x^2 + 2y}\}, \{\sqrt{y^2 + 2x}\})<C
Here {x}\{x\} denotes the fractional part of xx. For example, {3.14}=0.14\{3.14\} = 0.14.
Proposed by Anton Trygub