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2009 integers around a circle, weird mean Puerto Rico Ibero IMO TST 2009.5

Source:

September 16, 2021
algebranumber theory

Problem Statement

The weird mean of two numbers a a and b b is defined as 2a2+3b25 \sqrt {\frac {2a^2 + 3b^2}{5}}. 2009 2009 positive integers are placed around a circle such that each number is equal to the the weird mean of the two numbers beside it. Show that these 2009 2009 numbers must be equal.