Maths Olympiad Prep

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Problem 2147

National Olympiad second round; IMO P1/P4
Algebra Difficulty 7.8 Find the answer USAMO

Let R>0\mathbb{R}_{>0} be the set of all positive real numbers. Find all functions f:R>0R>0f:\mathbb{R}_{>0} \to \mathbb{R}_{>0} such that for all x,yR>0x,y\in \mathbb{R}_{>0} we have f(x)=f(f(f(x))+y)+f(xf(y))f(x+y).f(x) = f(f(f(x)) + y) + f(xf(y)) f(x+y).

A number or a short expression. Fractions can be typed as 3/2, and spacing doesn't matter.

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