Using Tables to Determine Limits

  • Thread starter Thread starter nycmathguy
  • Start date Start date
  • Tags Tags
    Limits
Click For Summary
SUMMARY

The discussion focuses on determining the limit of the function f(x) = x + 3 as x approaches 2 from both the left and right. The left-hand limit (LHL) is calculated using values 1.9, 1.99, and 1.999, yielding f(x) values of 4.9, 4.99, and 4.999, respectively, which round to 5. The right-hand limit (RHL) is calculated using values 2.001, 2.01, and 2.1, resulting in f(x) values of 5.001, 5.01, and 5.1, which also round to 5. Therefore, the limit of f(x) as x approaches 2 is conclusively 5, as both LHL and RHL equal 5.

PREREQUISITES
  • Understanding of limits in calculus
  • Familiarity with linear functions
  • Basic skills in evaluating functions
  • Knowledge of rounding numbers
NEXT STEPS
  • Study the concept of limits in calculus, focusing on one-sided limits
  • Practice evaluating limits using different functions
  • Explore the epsilon-delta definition of limits
  • Learn about continuity and its relationship to limits
USEFUL FOR

Students in calculus courses, educators teaching limits, and anyone seeking to strengthen their understanding of evaluating limits using tables.

nycmathguy
Homework Statement
Use tables to determine a limit.
Relevant Equations
Linear Equation
:: Tables and Limits

Complete a table for f(x) = x + 3 as x→2 from the right and left.

As x tends to 2 from the left side, the given values for x are: 1.9, 1.99, 1.999.

As x tends to 2 from the right side, the given values for x are: 2.001, 2.01, 2.1.

Let me see if I can do this.

I think this question is just an evaluation exercise. I got to plug all the given x-values to evaluate f(x) as x tends to 2.

Each value of x from the left and right gets closer and closer to 2 but f(x) never reaches 2. By this I mean f(x) gets extremely close to 2 but never becomes 2. Is this not the basic limit idea as taught in first semester calculus?

Moving on. This reply is going to drag. How do you think I feel using my cell phone to type all this work?

Our function f(x) = x + 3 is a line.

As x tends to 2 from the left side, the given values for x are: 1.9, 1.99, 1.999.

f(x) = x + 3

f(1.9) = 1.9 + 3 = 4.9

f(1.99) = 1.99 + 3 = 4.99

f(1.999) = 1.999 + 3 = 4.999

Rounding to the units place, I get 5.
The limit is 5.

Yes?

As x tends to 2 from the right side, the given values for x are: 2.001, 2.01, 2.1.

f(x) = x + 3

f(2.001) = 2.001 + 3 = 5.001

f(2.01) = 2.01 + 3 = 5.01

f(2.1) = 2.1 + 3 = 5.1

Rounding to the units place, I get 5.

I conclude the limit is 5.

All of this tells me that the LHL = RHS = 5.

The limit of f(x) as x-->2 is 5.

You say?

Now to make a table.

For the table as x-->2 from the left side:

x: 1.9... . .1.99...1.999
f(x): 4.9. 4.99. 4.999

For the table as x-->2 from the right side:

x: 2.001...2.01...2.1
f(x): 5.001...5.01...5.1

Trust me, I don't plan to do another "complete a table" problem for a very long time. Is any of this right?
 
  • Like
Likes   Reactions: Delta2
Physics news on Phys.org
nycmathguy said:
Homework Statement:: Use tables to determine a limit.
Relevant Equations:: Linear Equation

f(2.001) = 2.001 + 3 = 5.001

f(2.01) = 2.01 + 3 = 5.01

f(2.1) = 2.1 + 3 = 5.1

It would be to rearrange inverse order

f(2.1) = 2.1 + 3 = 5.1

f(2.01) = 2.01 + 3 = 5.01

f(2.001) = 2.001 + 3 = 5.001

f(2.0001)= ...
 
  • Like
Likes   Reactions: nycmathguy
anuttarasammyak said:
It would be to rearrange inverse order

f(2.1) = 2.1 + 3 = 5.1

f(2.01) = 2.01 + 3 = 5.01

f(2.001) = 2.001 + 3 = 5.001

f(2.0001)= ...

Thank you for the correction. Everything else is ok. Right?
 

Similar threads

Replies
3
Views
1K
Replies
5
Views
1K
  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 7 ·
Replies
7
Views
1K
  • · Replies 10 ·
Replies
10
Views
1K
  • · Replies 6 ·
Replies
6
Views
1K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 12 ·
Replies
12
Views
3K
  • · Replies 2 ·
Replies
2
Views
1K
Replies
2
Views
2K