Inequality with absolute value

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Discussion Overview

The discussion revolves around how to express certain inequalities involving absolute values. Participants explore different inequalities and their representations, focusing on the transformation of inequalities into absolute value form.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant presents the inequality x < -5 or 8 < x and seeks guidance on how to express it using absolute values.
  • Another participant suggests a resource for further assistance on inequalities.
  • A different participant explains that the inequality can be represented as |x - 3/2| > 13/2, indicating that all points satisfying the inequality are greater than 13/2 units from the midpoint of the interval.
  • One participant agrees with the explanation provided, noting it aligns with a book answer.
  • A follow-up problem is introduced, asking how to express the inequality 1 < x < 9 in absolute value form, leading to the conclusion that |x - 5| < 4, with the midpoint of the interval being 5.

Areas of Agreement / Disagreement

Participants generally agree on the methods of expressing inequalities with absolute values, but there is no consensus on the initial inequality presented by the first participant.

Contextual Notes

The discussion includes varying interpretations of how to approach the transformation of inequalities into absolute value form, with some assumptions about the midpoint and distance from it being made without explicit agreement on all details.

karush
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Write as one inequality with an absolute value

x<-5 or 8<x

not sure how you introduce the absolute value in this to solve it.

thanks ahead
 
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Re: ineqaulity with absolute value

Hello, karush!

"Write as one inequality with an absolute value: .x < -5 .or .8 < x."
Code:
            : - - 13/2 - - : - - 13/2 - - :
      ======o--------------*--------------o======
           -5             3/2             8
Note that the midpoint of the interval is 3/2.

All the points satisfying the inequality are greater than 13/2 units from the midpoint.

Therefore: .|x - 3/2|. > . 13/2
 
Re: ineqaulity with absolute value

yes that's makes sense that the book answer also
 
Re: ineqaulity with absolute value


To follow up on this topic, consider this problem.

Write as one inequality with an absolute value: .$1\, <\,x\,<\,9$
Note that the midpoint of the interval is 5.

Code:
          : - - 4 - - : - - 4 - - :
      ----o===========*===========o----
          1           5           9

We see that the values of $x$ are all within 4 units of 5.

Therefore: .$|x - 5| \:<\:4$
 

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