2006 IMO Problems/Problem 3

Problem

Determine the least real number such that the inequality $\left|ab\left(a^{2}-b^{2}\right)\right+bc\left(b^{2}-c^{2}\right)+ca\left(c^{2}-a^{2}\right)|\leq M\left(a^{2}+b^{2}+c^{2}\right)^{2}$ (Error compiling LaTeX. Unknown error_msg) holds for all real numbers and

Solution

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