5.6.28 find domain of x in ABS

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Discussion Overview

The discussion revolves around the mathematical problem of finding the domain of \( x \) in the inequality \( |2x-5|<9 \). Participants explore the notation used in the problem and the implications of different formatting choices.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant presents a solution approach by dividing the inequality into two cases and derives the interval \( -2 < x < 7 \), expressing some uncertainty about the correctness of this result.
  • Another participant questions the notation "Find x \quad" and seeks clarification on its meaning, leading to a discussion about LaTeX formatting.
  • There is a suggestion to rephrase the problem for clarity, emphasizing that the notation might confuse students, particularly in an algebra context.
  • Some participants discuss their preferences for spacing in mathematical notation, with one mentioning the use of different symbols like \(\in\) and ~ for separation.
  • A participant shares a personal anecdote about their experience in a 7th-grade math class, indicating a long history with mathematical notation.

Areas of Agreement / Disagreement

Participants express differing views on the clarity of the notation used in the problem and its potential impact on students. There is no consensus on the best way to format the problem statement.

Contextual Notes

Some participants note that the use of certain symbols or formatting might not be universally understood, which could affect comprehension in educational settings.

Who May Find This Useful

This discussion may be of interest to educators, students learning about inequalities, and those involved in mathematical notation and formatting conventions.

karush
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$\tiny{\textit{5.6.28}}$
Find $x \quad |2x-5|<9$
divide into 2 solution sets
$\begin{array}{rl|rl}
(2x-5)&=9&-(2x-5)&=9 \\
2x&=14&-2x&=4 \\
x&=7&x&=-2
\end{array}$
x is $-2<x<7$
kinda maybe...
 
Last edited:
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karush said:
Find x \quad $|2x-5|<9$
What does x \quad mean?

-Dan
 
topsquark said:
What does x \quad mean?

-Dan
oh its a latex H space A \quad B is $A \quad B$
 
karush said:
oh its a latex H space A \quad B is $A \quad B$
I'm not seeing anything between A and B. Just go ahead and write it as: Find all x such that |2x - 5| < 9. Or Find all x s.t. |2x - 5| < 9.

You answer looks good to me. Why are you not sure it's right?

-Dan

Wait. Are you trying to write [math] x \in |2x - 5| < 9[/math]? You are looking for a lower case epsilon. But you can simply write it as \in.

If this is the case your notation doesn't really work all that well. Just go ahead and write it like I suggested above.

-Dan
 
Last edited by a moderator:
well actually when you start the question with "Find x" sometime the x looks it is part of the equation therefore it needs to separated from it,,,, \quad is often used to do this... just markup stuff...:cool:

Find x $\quad |2x-5|<9$

using $\in$ in an algebra class might knock some students off the saddle
 
karush said:
well actually when you start the question with "Find x" sometime the x looks it is part of the equation therefore it needs to separated from it,,,, \quad is often used to do this... just markup stuff...:cool:

Find x $\quad |2x-5|<9$

using $\in$ in an algebra class might knock some students off the saddle
Oh! I see. I just use ~ for my spacer.

I was introduced to [math]\in[/math] in 7th grade. But it averages itself out... there was also a bunch of stuff they didn't do either.

-Dan
 
i was in the 7th grade in 1957 it was a dense class
 

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