Using the squeeze theorem to solve a limit

In summary, the problem is to solve the limit \lim_{x\to3}\left((x^2-9)\frac{x-3}{|x-3|}\right) by using the squeeze theorem, and the given expression is simplified to \displaystyle (x^2-9)\frac{x-3}{|x-3|}. It is then shown that this expression is always greater than or equal to 0 for x > 0 and less than 8|x-3| for 2 < x < 4, which can be used to solve the limit.
  • #1
LOLItsAJ
5
0

Homework Statement


I have a limit, which when substitution is used the indeterminate form 0/0 occurs. I've been asked to solve the limit by using the squeeze theorem. I really have no idea where to take this.


Homework Equations


Lim (x[itex]^2[/itex]-9)(x-3[itex]/[/itex]|x-3|)
x[itex]\rightarrow[/itex]3


The Attempt at a Solution


I've tried so many attempts at this problem, posting all my work would be massive.
 
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  • #2
LOLItsAJ said:

Homework Statement


I have a limit, which when substitution is used the indeterminate form 0/0 occurs. I've been asked to solve the limit by using the squeeze theorem. I really have no idea where to take this.


Homework Equations


Lim (x[itex]^2[/itex]-9)(x-3[itex]/[/itex]|x-3|)
x[itex]\rightarrow[/itex]3


The Attempt at a Solution


I've tried so many attempts at this problem, posting all my work would be massive.
Are you sure the problem is what you state, which is equivalent to [itex]\displaystyle \lim_{x\to3}\left((x^2-9)\left(x-\frac{3}{|x-3|}\right)\right)\,,[/itex] or is it [itex]\displaystyle \lim_{x\to3}\left((x^2-9)\frac{x-3}{|x-3|}\right)\,?[/itex]
 
  • #3
It's your second one. I'm a bit confused by the format used on the forum.
 
  • #4
It appears to me that simplifying the expression using algebra works better than using the squeeze theorem, but ...

Certainly, [itex]\displaystyle (x^2-9)\frac{x-3}{|x-3|}\ge0[/itex] for x > 0.

Can you show that [itex]\displaystyle (x^2-9)\frac{x-3}{|x-3|}< 8|x-3|[/itex] for 2 < x < 4 ?
 

FAQ: Using the squeeze theorem to solve a limit

What is the squeeze theorem?

The squeeze theorem, also known as the sandwich theorem, is a mathematical theorem that is used to prove the limit of a function by showing that it is squeezed between two other functions whose limits are known.

How do you use the squeeze theorem to solve a limit?

To use the squeeze theorem, you must first identify a function that is being squeezed between two other functions. Then, you must prove that the two outer functions have the same limit. Finally, you can conclude that the middle function must also have the same limit.

What are the conditions for using the squeeze theorem?

The two outer functions must have the same limit at the point of interest, and the middle function must be sandwiched between the two outer functions. Additionally, the functions must be defined on a closed interval around the point of interest.

Can the squeeze theorem be used to solve any limit?

No, the squeeze theorem can only be used to solve limits where the function is being squeezed between two other functions. It cannot be used for limits that involve division by zero or other undefined operations.

Are there any limitations to using the squeeze theorem?

The squeeze theorem can only prove the existence of a limit, it cannot determine the value of the limit. Additionally, it can only be used for one-sided limits, so it is not applicable for solving limits at points of discontinuity.

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