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equation

Source: Romania District Olympiad 2013,grade X(problem 1)

March 14, 2013
algebra proposedalgebra

Problem Statement

Let a,bRa,b\in \mathbb{R} and zC\Rz\in \mathbb{C}\backslash \mathbb{R} so that ab=a+b2z\left| a-b \right|=\left| a+b-2z \right|. a) Prove that the equation zax+zˉbx=abx{{\left| z-a \right|}^{x}}+{{\left| \bar{z}-b \right|}^{x}}={{\left| a-b \right|}^{x}}, with the unknown number xRx\in \mathbb{R}, has a unique solution. b) Solve the following inequation zax+zˉbxabx{{\left| z-a \right|}^{x}}+{{\left| \bar{z}-b \right|}^{x}}\le {{\left| a-b \right|}^{x}}, with the unknown number xRx\in \mathbb{R}. The Mathematical Gazette