An exponential number algebra problem

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Discussion Overview

The discussion revolves around a mathematical problem involving the expression \( an - bn \) in terms of the difference \( C = a - b \) and a variable \( n \). Participants explore the feasibility of eliminating variables \( a \) and \( b \) to express the equation solely in terms of \( C \) and \( n \). The context includes a practical application related to the resonance frequency of a resonator affected by changes in length due to applied force.

Discussion Character

  • Mathematical reasoning
  • Experimental/applied

Main Points Raised

  • One participant asserts that it is not possible to eliminate \( a \) and \( b \) completely from the expression \( an - bn \), providing examples where different pairs of \( a \) and \( b \) yield the same \( C \) but different results for \( a^n - b^n \).
  • Another participant suggests that while \( an - bn \) can be rewritten to include a factor of \( (a - b) \), complete elimination of \( a \) and \( b \) is not achievable.
  • A participant introduces a practical scenario involving a resonator, explaining how the resonance frequency changes with deformation and relating it to the variables \( a \), \( b \), \( n \), and \( C \).
  • There are inquiries about the roles of \( a \) and \( b \) in the context of the resonator problem.
  • Logarithmic transformation is suggested as a potential approach to handle the relationship between the variables, specifically in the context of resonance frequency.

Areas of Agreement / Disagreement

Participants generally agree that eliminating \( a \) and \( b \) completely from the expression is not possible, but there are differing views on how to manipulate the expression and the implications of the practical example provided.

Contextual Notes

The discussion includes limitations regarding the assumptions made about the variables and the dependence on specific definitions related to the resonance frequency and material properties.

Edge5
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Let a,b,c and n are real numbers.a-b = C
I want to get rid of a,b and find the following expression in terms of C and n. How can I do that?
(an-bn)= ? (in terms of C and n)

Thank you.
 
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You can't.
Simple example: a=2, b=1 and a=1, b=0 both lead to C=1, but a2-b2 is different for the two cases.

You can rewrite an-bn to have a factor of (a-b) but you won't get rid of a and b completely.

What is the context of this question?
 
mfb said:
You can't.
Simple example: a=2, b=1 and a=1, b=0 both lead to C=1, but a2-b2 is different for the two cases.

You can rewrite an-bn to have a factor of (a-b) but you won't get rid of a and b completely.

What is the context of this question?

I have a resonator and the resonance frequency (w) of it is given by w=A(L-1.5) where A is a constant and L is the length. When I apply a force the resonance frequency changes because length of the beam changes due to deformation. I need to find the change in resonance frequency as a function of change in length.
That's why I said winitial = ALinitial-1.5
and ALfinal-1.5
Lfinal-Linitial = (Linitial.Ftensile)/(EAcrossection)
Where E is the young modulus and A is the area.
In my question a and b were Linitial and Lfinal
n was -1.5
C was (Linitial.Ftensile)/(EAcrossection)
 
Last edited:
So where are the ##a## and ##b## in your story ?
 
BvU said:
So where are the ##a## and ##b## in your story ?
In my question a and b were Linitial and Lfinal
 
So take logarithms ! $$\ln\omega = \ln A - 1.5\ln L$$
 
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BvU said:
So take logarithms ! $$\ln\omega = \ln A - 1.5\ln L$$
I will try thanks
 

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