Using Tables to Determine Limits

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The discussion focuses on determining the limit of the function f(x) = x + 3 as x approaches 2 from both the left and right sides. As x approaches 2 from the left (1.9, 1.99, 1.999), the function values approach 5, while approaching from the right (2.001, 2.01, 2.1) also yields values that round to 5. The conclusion drawn is that the left-hand limit (LHL) and right-hand limit (RHL) both equal 5, confirming that the limit of f(x) as x approaches 2 is indeed 5. The conversation also includes a brief mention of the challenges of typing on a cell phone while working through the problem. Overall, the analysis confirms a solid understanding of limits in calculus.
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?
 
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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)= ...
 
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?
 

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