Is There an Algebraic Solution for 36=X^X?

  • Context: Undergrad 
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Discussion Overview

The discussion revolves around the equation 36 = X^X, specifically exploring whether there exists an algebraic solution to this equation. Participants share their attempts at solving it, including graphical and numerical methods.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant expresses difficulty in solving the equation algebraically and mentions a graphical solution around 3.15.
  • Another participant asserts that an algebraic solution is not possible.
  • In contrast, a different participant claims that the Lambert-W Function can be used to solve the equation algebraically.
  • A further contribution introduces a function f(x) = x^x - 36 and describes a numerical method to find a zero of this function, suggesting a solution in the interval (3.1, 3.2) around 3.13564239388907368.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the existence of an algebraic solution, with some asserting it is impossible while others propose methods that could lead to a solution.

Contextual Notes

The discussion includes various approaches to the problem, but the reliance on specific functions and numerical methods introduces assumptions that are not universally accepted among participants.

Freespader
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I came up with an idea for an equation, which follows: 36=X^X. I tried solving it, but I couldn't. I found the graphically (3.15, if I recall correctly), but I want to know if there's a way to solve it algebraically.
 
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Freespader said:
… I want to know if there's a way to solve it algebraically.

nope! :redface:
 
Actually, you can, but you need to use the Lambert-W Function.
 
Let f(x):=x[itex]^{x}[/itex] - 36, (f(x) is continuous, f(3.1) < 0, f(3.2) > 0) we can apply

the 'half intervall' function I implemented in my ARIBAS_W workbench, to find the zero of f(x)

in the intervall (3.1,3.2) as: 3.13564239388907368
 

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