How to represent this absolute value inequality with constants?

Click For Summary
SUMMARY

The discussion focuses on representing the absolute value inequality \(0 < |x - a| < \delta\) graphically on the x-axis. Participants clarify that the constant "a" does not require separation into different cases, as it is not conditioned. Instead, a single interval representation, \( (a - \delta, a + \delta) \), suffices to illustrate the concept. Additionally, the correct notation for excluding points, such as \(x = a\), involves using round brackets in the interval notation.

PREREQUISITES
  • Understanding of absolute value inequalities
  • Familiarity with interval notation
  • Basic graphing skills on the x-axis
  • Knowledge of epsilon-delta definitions in calculus
NEXT STEPS
  • Study the epsilon-delta definition of limits in calculus
  • Learn about interval notation and its graphical representation
  • Explore how to graph inequalities on the x-axis
  • Investigate the implications of excluding points in interval notation
USEFUL FOR

Students learning calculus, mathematics educators, and anyone interested in understanding graphical representations of inequalities.

kenny1999
Messages
235
Reaction score
5
Homework Statement
absolute value
Relevant Equations
inequality
see attached image, it asks to repesent it in x-graph
constant "a" isn't conditioned.
Do I need to separate it into a few cases of the constant a and represent each in one x-graph?
Screenshot 2021-03-09 140649.png
 
Last edited by a moderator:
Physics news on Phys.org
What do you mean by an x-graph? Do you mean on the x-axis?
 
  • Like
Likes   Reactions: Delta2
You should read that the formula means x is around a within distance ##\epsilon##.
 
  • Like
Likes   Reactions: Delta2
PeroK said:
What do you mean by an x-graph? Do you mean on the x-axis?

yes. Sorry I am not in English language
 
anuttarasammyak said:
You should read that the formula means x is around a within distance ##\epsilon##.

a isn't conditioned, e.g. >0 or <0

so do I need to separate into a few cases and draw the graph??
 
OK . This is what I have done, I don't know if I am correct. I am teaching my cousin, but I have left school for 20 years
12231231313131.jpg
 
Last edited by a moderator:
  • Like
Likes   Reactions: PeroK
Another question , I avoid starting a new topic. Am I correct??
66.jpg
 
Last edited by a moderator:
kenny1999 said:
OK . This is what I have done, I don't know if I am correct. I am teaching my cousin, but I have left school for 20 years
I think all you need to do is show one interval ##(a - \delta, a + \delta)##. You don't need all those different cases. The point ##x = 0## is not important here.
 
  • Like
Likes   Reactions: FactChecker and kenny1999
kenny1999 said:
Another question , I avoid starting a new topic. Am I correct??
I guess that's ##0 < |x - a| < \delta##?
 
  • #10
To make your diagram more clear, show ##a## on it. Then show ##a-\delta## and ##a+\delta##. There is no reason to even show where anything else, like ##x=0##, is. Then one diagram takes care of all the cases.
 
  • Like
Likes   Reactions: kenny1999
  • #11
PeroK said:
I think all you need to do is show one interval ##(a - \delta, a + \delta)##. You don't need all those different cases. The point ##x = 0## is not important here.

Hi, did you mean I do not have to consider the possible ranges of value of a ? (Since a isn't conditioned but the delta is given that >0, that's why I am wondering if I need to separate a into different ranges of value
 
  • #12
PeroK said:
I guess that's ##0 < |x - a| < \delta##?
No, "Another question" is really another, not related to the first question, yes the first question was ##0 < |x - a| < \delta##

I think the second question does NOT include x=0. How to draw a symbol to represent that x=0 isn't included?? an arrow??
 
  • #13
kenny1999 said:
Hi, did you mean I do not have to consider the possible ranges of value of a ? (Since a isn't conditioned but the delta is given that >0, that's why I am wondering if I need to separate a into different ranges of value
You don't have to consider different values for ##a##.
 
  • #14
kenny1999 said:
No, "Another question" is really another, not related to the first question, yes the first question was ##0 < |x - a| < \delta##

I think the second question does NOT include x=0. How to draw a symbol to represent that x=0 isn't included?? an arrow??
It's ##x =a## that is excluded. I would just use ##(a-\delta, a)(a, a + \delta)## with round brackets to show the end points are excluded.
 

Similar threads

Replies
11
Views
3K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
4
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
5
Views
2K
Replies
6
Views
3K