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|x+a|+|x+y+b|+|y+c|>|x|+|x+y|+|y| - All-Russian MO 1999 Regional (R4) 11.5

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September 25, 2024
algebrainequalities

Problem Statement

Are there real numbers a,ba, b and cc such that for all real xx and yy the following inequality holds: x+a+x+y+b+y+c>x+x+y+y?|x + a| + |x + y + b| + |y + c| > |x| + |x + y| + |y|?