Confused about equations with absolute values

Click For Summary

Discussion Overview

The discussion revolves around the interpretation of equations involving absolute values, specifically the transformation of the equation |y|=e^c|x| into y=\pm e^cx. Participants seek clarification on the reasoning behind this transformation and its implications.

Discussion Character

  • Conceptual clarification, Technical explanation, Debate/contested

Main Points Raised

  • One participant expresses confusion about the transformation of |y|=e^c|x| to y=\pm e^cx and requests an explanation.
  • Another participant proposes that the equation can be interpreted as |y| = e^c|x| = |e^cx|, suggesting there are four cases to consider for y.
  • The four cases outlined include: y = e^cx, y = -e^cx, -y = e^cx, and -y = -e^cx, with the inner two and outer two being equivalent.
  • A further simplification is suggested, leading to the conclusion that y can be expressed as y = \pm e^cx.
  • Another participant introduces a simpler example, |y|=|x|, to prompt consideration of what values of y would satisfy the equation given a known value of x.
  • A technical note is made regarding the use of LaTeX formatting for clarity in mathematical expressions.

Areas of Agreement / Disagreement

The discussion reflects a lack of consensus on the understanding of the transformation involving absolute values, with participants presenting different interpretations and approaches to the problem.

Contextual Notes

Participants have not fully resolved the assumptions underlying the transformation of absolute values, nor have they clarified the implications of the four cases presented.

Nat3
Messages
69
Reaction score
0
My calc book rewrites this equation:

|y|=e^c|x|

As this:

y=\pm e^cx

But that doesn't really make any sense to me. I know I should understand why we're allowed to do that, but I don't. Could someone please try to explain it to me?

I really appreciate your help, thanks!
 
Physics news on Phys.org
Is it because:

|y| = e^c|x| = |e^cx|

And there are four cases:

y = e^cx

y = -e^cx

-y = e^cx

-y = -e^cx

With the inner two and outer two being equivalent, respectively, resulting in:

y = e^cx

y = -e^cx

Which can be written as (?):

y = \pm e^cx
 
First consider the simpler equation

|y|=|x|

Suppose you know the value of x. What values of y would make the equation true?
 
Nat3, in LaTex, use { } to group. That is, use e^{cx} to get e^{cx}. e^cx gives e^cx.
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 16 ·
Replies
16
Views
3K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 15 ·
Replies
15
Views
4K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 32 ·
2
Replies
32
Views
2K