Solve $2+5\ln{x}=21$: Find $x$

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Discussion Overview

The discussion revolves around solving the equation $2+5\ln{x}=21$, focusing on the manipulation of logarithmic expressions and the interpretation of exponents. Participants explore different approaches to isolate the variable and express the solution in terms of the natural exponential function.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Conceptual clarification

Main Points Raised

  • One participant presents a step-by-step approach to isolate $\ln{x}$ and expresses concern about seeing a fraction as an exponent.
  • Another participant suggests that understanding $\ln(x) = a$ leads to $x = e^a$, proposing this perspective might clarify the situation.
  • A participant emphasizes that exponents can take various forms, including integers, fractions, irrational numbers, or even complex numbers.
  • There is a humorous remark about exponents potentially being matrices, adding a light-hearted tone to the discussion.
  • A participant shares a link to a collection of pre-calculus problems, indicating a broader context of educational resources and engagement with students.

Areas of Agreement / Disagreement

The discussion does not reach a consensus on the best approach to the problem, and participants express varying levels of understanding and interpretation of logarithmic concepts.

Contextual Notes

Some assumptions about the properties of logarithms and exponents are present, but they are not explicitly stated or agreed upon by all participants.

karush
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$\tiny{6.1.07 kilana HS}$
Solve $2+5\ln{x}=21$
\$\begin{array}{rlll}
\textsf{isolate} &\ln{x} &=\dfrac{19}{5} &(1)\\
\textsf{then} & &= &(2)\\
\textsf{then} & &= &(3)\\
\textsf{hence} & &= &(4)
\end{array}$
ok for (2) I presume e thru then calculate for x
just strange to see a fraction as an e exponent
tryin array on these no sure if its better :unsure:
 
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[math]ln(x) = a \implies x = e^a[/math]

Does it make more sense if you think of it that way?

-Dan
 
You understand that an exponent is just a number, don't you? An exponent can be an integer, or a fraction, an irrational number, or a complex number.
 
roger
 
Country Boy said:
You understand that an exponent is just a number, don't you? An exponent can be an integer, or a fraction, an irrational number, or a complex number.
Or even a matrix... Buwahahahaha!

-Dan
 
https://dl.orangedox.com/QS7cBvdKw55RQUbliE

this is preliminary test to see if this works
but anyway I am trying to make a collection of 25 or more pre calc problems that came form students here on Oahu
I run a counter on the views and downloads, an earlier count it was over 50,000 on the MHB views
so it has been an awsome help. Hopefully more student from the island will join the forum when school starts up again
Im using OrangeDox because it keeps track of what happens with you posted files
 

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