Working on evaluating an 'e' equation to find the domain of an equation

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Discussion Overview

The discussion revolves around evaluating the domain of the inequality $$1 \ne e^{1-x^2}$$. Participants explore the implications of this inequality and the methods to analyze it, including the use of logarithms.

Discussion Character

  • Exploratory
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant asks how to find the domain of the inequality $$1 \ne e^{1-x^2}$$.
  • Another suggests taking the natural logarithm of both sides as a method to evaluate the inequality.
  • A participant points out that the expression is not a function or equation but an inequality, emphasizing the need for clarity in terminology.
  • One participant derives that taking the logarithm leads to the expression $$0 \ne 1 - x^2$$, concluding that $$x \ne 1$$.
  • Another participant corrects this by noting that the case of $$x = -1$$ was missed, indicating that the correct interpretation leads to $$x \ne 1$$ AND $$x \ne -1$$.
  • A later reply introduces the possibility of complex solutions, suggesting that if $$x = \sqrt{1+2\pi i}$$, then $$\exp(1-x^2) = 1$$, which complicates the analysis further.

Areas of Agreement / Disagreement

Participants express differing views on the completeness of the analysis, with some emphasizing the need to consider multiple solutions and others focusing on specific real values. The discussion remains unresolved regarding the full set of solutions.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the domain, particularly concerning the consideration of complex numbers and the implications of the inequality.

tmt1
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Find the domain of the equation

$$1 \ne e^{1-x^2}$$

Is there a way to evaluate this function?
 
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tmt said:
$$1 \ne e^{1-x^2}$$

Is there a way to evaluate this function?

Hint: take $\ln$ on both sides.

Btw, this is not a function nor an equation. It's called an inequality.Moderator's note: I have moved part of your title to your opening post.
Please put all relevant information in your post and do not put part of the question only in the title.
 
tmt said:
Find the domain of the equation

$$1 \ne e^{1-x^2}$$

Is there a way to evaluate this function?

Think about $e^x$. When does it take the value $1$? Can you use this?
 
I like Serena said:
Hint: take $\ln$ on both sides.

Btw, this is not a function nor an equation. It's called an inequality.Moderator's note: I have moved part of your title to your opening post.
Please put all relevant information in your post and do not put part of the question only in the title.

so

$$ln1 \ne ln{e ^{1 - x^2}}$$

which goes to

$$0 \ne 1- x^2$$

which means

$$x \ne 1$$

Is this right?
 
You have missed the case of $x = -1$. Note that $\log$-ing both side (which you have done correctly (Yes)), you get

$$0 \neq x^2 - 1$$

Note that $x^2 - 1$ has TWO solutions : $x = 1$ and $x = -1$. Thus, $x \neq 1$ AND $x \neq -1$

PS : I presume you were asked to find real $x$s? If not, there are also a lot of cases you are missing. For example, if $x = \sqrt{1+2\pi i}$ then $\exp(1-x^2) = 1$.
 

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