Logarithm + Nepper's number Exercise

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    Exercise Logarithm
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Discussion Overview

The discussion revolves around solving the equation 2e^(-x) = 3e^(0.1x). Participants explore different methods to isolate x and express it in logarithmic form. The conversation includes attempts at mathematical manipulation and clarification of logarithmic properties.

Discussion Character

  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant begins by stating their difficulty in solving the equation and suggests a potential form for the answer.
  • Another participant proposes multiplying both sides by e^x to simplify the equation to 2 = 3e^(1.1x).
  • A subsequent reply indicates the conversion from exponential to logarithmic form, leading to the expression 1.1x = log e^(2/3).
  • Another participant reiterates the logarithmic transformation and arrives at x = [(2/3) log e]/1.1, questioning its correctness.
  • A later reply clarifies the logarithmic notation, suggesting that x = ln(2/3)/1.1 is the correct form, while also providing guidance on using LaTeX for formatting.
  • One participant expresses relief upon realizing they misread the logarithmic notation in their book, confirming their understanding after reworking the exercise.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the final expression for x, as different logarithmic forms are presented. There is also uncertainty regarding the correct notation for logarithms.

Contextual Notes

There are unresolved aspects regarding the notation of logarithms and the participants' understanding of the transformation steps. Some participants express confusion over the use of log versus ln.

Velo
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" Solve the equation:

2e^(-x) = 3e^(0.1x) "

I've been fiddling around with this and I have no idea what I'm supposed to do. I know the final answer should be something like:
x = [(2/3)log e] / 1,1

The only step I've managed to do was:
(2/3) x e^(-x) = e^(0.1x)

But after that, I don't know how to get the x out of the exponential.. Help would be appreciated :')
 
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We are given to solve:

$$2e^{-x}=3e^{0.1x}$$

My first step would be to multiply though by $e^x\ne0$ to get:

$$2=3e^{1.1x}$$

Now divide though by 3:

$$\frac{2}{3}=e^{1.1x}$$

Next, what do you get when converting from exponential to logarithmic form?
 
Hm...

1.1x = log e ^ (2/3) <=>
x = [log e ^ (2/3)]/1.1 <=>
x = [(2/3) log e]/1.1

Which was the solution :o Is that right? Also, sorry, I'm having trouble using the latex thingy ><
 
Velo said:
Hm...

1.1x = log e ^ (2/3) <=>
x = [log e ^ (2/3)]/1.1 <=>
x = [(2/3) log e]/1.1

Which was the solution :o Is that right? Also, sorry, I'm having trouble using the latex thingy ><

Let's go back to:

$$\frac{2}{3}=e^{1.1x}$$

Now recall that:

$$a=b^c\implies c=\log_b(a)$$

And so we may write:

$$1.1x=\ln\left(\frac{2}{3}\right)$$

And then on dividing though by 1.1, we get:

$$x=\frac{\ln\left(\dfrac{2}{3}\right)}{1.1}$$

To use $\LaTeX$, you need to enclose your code with tags. The simplest way is to click the $\Sigma$ button on our toolbar, and then the cursor will be located in between the resulting $$$$ tags, and you can add your code there. You will find most symbols/commands you need to the right of the editor, in the "Quick $\LaTeX$" tool, and you can get quick previews of your code in our "$\LaTeX$ Live Preview" tool.
 
Ohhh, I get it now.. I read the book wrong too :') The solution had $$ \log_e(\frac{2}{3}) $$ and not $$\log(\frac{2}{3})$$.. I spent so much time wondering where that log had come from :') I tried redoing that exercise and the next in my notebook and I'm doing alright now x3 Thank you very much! :D
 

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