MathDB

21

Part of 1985 IMO Longlists

Problems(1)

IMO LongList 1985 CZS2 - At most nine elements

Source:

9/10/2010
Let AA be a set of positive integers such that for any two distinct elements x,y∈Ax, y\in A we have ∣x−y∣≥xy25.|x-y| \geq \frac{xy}{25}. Prove that AA contains at most nine elements. Give an example of such a set of nine elements.
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