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We have: $$ x^{x^{x^{ x^{x ^{x ^{\dots}}}}}} = 2.$$

I tried a reasoning by recursion:

For $n=1$: \begin{align} x^x &= 2 \\ \implies x\ln x &= \ln 2 \end{align}

For $n=2$: \begin{align} x^{x^x} &= 2 \\ \implies x\ln x^x &= \ln 2 \\ \implies x^2\ln x &= \ln 2 \\ \end{align}

For an arbitrary $n$ we can solve: $$x^n \ln x = \ln 2 $$

But for $n \to \infty$, I can't seem to find something. Does anyone have an idea on how to tackle this problem?


marked as duplicate by Martin R, Community Apr 18 at 7:38

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Hint: If the solution exists then


The stuff in the power is equal to $2$ hence we can replace it by $2$.


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