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MathNet 2011 Question 1

Math Olympiad Vault · MathNet 2011

Question 1

Prove that for all real $x$ and $y$ the inequality
$$
|x + y| + |x + 1| + |y + 1| \geq 2
$$
holds. For what $x$ does there exist $y$ such that $|x+y|+|x+1|+|y+1| = 2$?