Proving these two functions intersect at 'a'

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Discussion Overview

The discussion centers around the intersection of two functions, ##f\left(x\right)=x^{a\left(a-x^3\right)}-a## and ##g\left(x\right)=a^{x\left(x-a^3\right)}-x##, specifically at the point ##x=a## for ##x>0##. Participants explore the possibility of mathematically proving this intersection and clarify the nature of the functions involved.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant claims that the functions always intersect at ##a## when ##x>0## and seeks a mathematical proof for this assertion.
  • Another participant suggests that the proof could be framed as demonstrating that ##f(a) = g(a)##.
  • A different participant questions the necessity of proving this, implying that it may be evident by substituting ##a## into the functions.
  • A later reply acknowledges a lack of clarity in the initial post and recognizes that proving ##f(a) = g(a)## would indeed demonstrate the intersection at ##x=a##.

Areas of Agreement / Disagreement

Participants express varying levels of certainty about the necessity of a formal proof, with some suggesting it is obvious while others seek clarification. The discussion does not reach a consensus on the need for proof versus the apparent nature of the intersection.

Contextual Notes

Some assumptions about the behavior of the functions and their intersections may not be fully explored, and the discussion does not resolve whether other intersection points exist beyond ##x=a##.

Saracen Rue
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Through experimental observations, I have found that the two functions ##f\left(x\right)=x^{a\left(a-x^3\right)}-a## and ##g\left(x\right)=a^{x\left(x-a^3\right)}-x## will always intersect at ##a## when ##x>0##. Is there a way to mathematically prove this? For instance, simultaneously solving the functions and simplifying the answer down to ##x=a## (Note: the functions sometimes also intersect at other locations besides ##[a, f(a)]##)
 
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Saracen Rue said:
Through experimental observations, I have found that the two functions ##f\left(x\right)=x^{a\left(a-x^3\right)}-a## and ##g\left(x\right)=a^{x\left(x-a^3\right)}-x## will always intersect at ##a## when ##x>0##. Is there a way to mathematically prove this? For instance, simultaneously solving the functions and simplifying the answer down to ##x=a## (Note: the functions sometimes also intersect at other locations besides ##[a, f(a)]##)

You mean prove that ##f(a) = g(a)##?
 
PeroK said:
You mean prove that ##f(a) = g(a)##?

Ah yes, expressing it that way does seem a lot clearer.
 
Isn't that obvious if you just plug in a for x?
 
Right, so it was midnight when I posted this and I wasn't in the most clear mindset. Looking back on this now I can see that by proving ##f(a)=g(a)## you also prove that ##f(x)## intersects ##g(x)## at ##x=a##. Sorry for this entire post.
 

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