Monday, 7 August 2017

functional equations - If f(x)=f(y) or f(fracx+y2)=f(sqrtxy), find f


Assume f:(0,)R is a continuous function such that for any x,y>0, f(x)=f(y) or f(x+y2)=f(xy). Find f.




I would work with each condition separately then combine later. So for f(x+y2)=f(xy) we see that the argument of each side is part of AM-GM, so that might help. I am wondering though how I might derive anything from the second equation since all I can see is that f(x+12)=f(x), which I don't see how helps.

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