Finding λ in an Exponential Equation: A Scientific Approach

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Homework Statement


I believe I need to rearrange this formula to find an equation for λ:

P2 / P1 = exp( - (z2 - z1)) / λ




Homework Equations


I think I need to differentiate and find the natural log of both sides then rearrange


The Attempt at a Solution


Differentiate to: ln(P2 / P1) = ( - (z2 - z1) / λ

Rearrange to: λ = - Δz / ln(P2 / P1)

Does that look right? I appear to be able to calculate it...
 
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annalise17 said:

Homework Statement


I believe I need to rearrange this formula to find an equation for λ:

P2 / P1 = exp( - (z2 - z1)) / λ




Homework Equations


I think I need to differentiate and find the natural log of both sides then rearrange


The Attempt at a Solution


Differentiate to: ln(P2 / P1) = ( - (z2 - z1) / λ

Rearrange to: λ = - Δz / ln(P2 / P1)

Does that look right? I appear to be able to calculate it...

Is this what you're meant to rearrange?
\frac{P_1}{P_2}=e^{-\frac{(Z_2 - Z_1)}{\lambda}}

Also, what are you differentiating?
 
Hmm I may not be differentiating anything actually! Sorry, my maths is lacking quite a bit so I mix up my terminology. But yes, that looks right (although I have P1 and P2 the other way around, I'll check that) I didn't know how to input it on here so attempted it in linear form.
 
annalise17 said:
Hmm I may not be differentiating anything actually! Sorry, my maths is lacking quite a bit so I mix up my terminology. But yes, that looks right (although I have P1 and P2 the other way around, I'll check that) I didn't know how to input it on here so attempted it in linear form.

Well if that's what you were asked to rearrange (Yes I got the P_1 and P_2 mixed up :P) Then that is right.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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