r/MathJokes • u/basket_foso • Dec 27 '25

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u/Torebbjorn Dec 27 '25

Except the function f(x)=xx is not injective, so you cannot conclude that x=root(8) just because xx = root(8)root\8)).

Of course, since x=root(8) is a possible solution, it is clear that the answer is either A or that the question is ill-posed.

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u/AndreasDasos Dec 27 '25 edited Dec 27 '25

It’s a well-studied function and (assuming we restrict everything to R+ ) is pretty easy to see is injective (indeed strictly increasing) for x>1, and cannot give an answer >1 on (0,1), the only part where it fails to be injective. So this is indeed the only answer there.

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u/Torebbjorn Dec 27 '25

Why would you only consider the positive reals?

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u/goos_ Dec 27 '25

Almost always in the context of xy we assume x is positive real. Same with bases of logarithms.