Discovering Limits: Solving for x Approaching Zero from the Left

  • Context: High School 
  • Thread starter Thread starter ashleyk
  • Start date Start date
  • Tags Tags
    Limit
Click For Summary

Discussion Overview

The discussion revolves around evaluating the limit of the expression (1 + (1/x)) as x approaches zero from the left. Participants explore different methods and reasoning for understanding this limit, focusing on the behavior of the function near zero.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Exploratory

Main Points Raised

  • One participant expresses uncertainty about applying previous limit techniques when approaching zero from the left.
  • Another participant prompts for intuition regarding the behavior of the expression as x approaches zero through negative values.
  • A suggestion is made to test values close to zero from the left, such as -0.1, -0.01, and -0.000001, to observe trends.
  • One participant proposes a substitution (y = 1/x) to analyze the limit, questioning what happens to y as x approaches zero.
  • A participant discusses the implications of dividing by a very small negative number, suggesting that 1/x will yield a very large value and raises the question of whether this value is positive or negative.
  • Another participant introduces the idea of creating a sign chart for the function (x + 1)/x to analyze the signs of the numerator and denominator separately.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the limit's value, and multiple approaches and interpretations remain under discussion.

Contextual Notes

Participants have not fully resolved the implications of their reasoning, and there are assumptions about the behavior of the function near zero that remain unexamined.

ashleyk
Messages
22
Reaction score
0
I need some help on my take home AP test. We have been taking the limit as the function approaches infinity but this is problem is when the limit approaches zero from the left...so I'm not sure if I can do that same steps.

Find the limit.

(limit as x approaches zero from the left) (1 + (1/x))


Any help would be great...
 
Physics news on Phys.org
Well, what is your gut feeling about the expression when x runs through the negative numbers up to 0 ?
 
Test points extremely close to zero from the left and see what trend they have.

-.1 , -.01 , -.000001
 
Or, if you feel more familiar with limits at infinity, let y= 1/x and look at 1+ y.

As x-> 0, what happens to y? what happens to 1+ y?
 
ashleyk said:
(limit as x approaches zero from the left) (1 + (1/x))


Any help would be great...

Well let's look at 1/x...just as in any fraction, you know that if you divide a number (here 1) by something real small you get something real big. So what do you think 1/0 will have as solution...it is going to be real big.

The second part will be to determin whether this "real big thing" is positive or negative. You can check this by making a sign chart of the function
[tex]\frac{x + 1}{x}[/tex] which is the same function that you gave, only written in a more convenient way to make sign charts. Just look at the numerator and the denominator apart. Can you make the sign chart of a function like ax +b ?

marlon
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
Replies
5
Views
2K
Replies
4
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 53 ·
2
Replies
53
Views
7K
  • · Replies 11 ·
Replies
11
Views
6K
Replies
5
Views
2K
  • · Replies 8 ·
Replies
8
Views
4K