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f (f (x)) = f (x) + x(maybe is old)

Source: 12-th Hungary-Israel Binational Mathematical Competition 2001

April 11, 2007
functionalgebra proposedalgebra

Problem Statement

Find all continuous functions f:R→Rf : \mathbb{R}\to\mathbb{R} such that for all x∈Rx \in\mathbb{ R}, f(f(x))=f(x)+x.f (f (x)) = f (x)+x.
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