How can I use this hint to help prove the limit using the definition?

In summary, to prove the limit \lim_{x\to 1^{+}}{\frac{x-3}{x-1}}=-\infty using its definition, the attempt was to set up the unequation \frac{x-3}{x-1} < - M and solve for x. However, this did not lead to the desired result of 1<x<1+\frac{2}{M+1}. A hint was given that M+3 = (M+1) + 2.
  • #1
scientifico
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Homework Statement


Hello, I have to prove, using the limit definition, that [itex]\lim_{x\to 1^{+}}{\frac{x-3}{x-1}}=-\infty[/itex]


The Attempt at a Solution


I've set this unequation [itex]\frac{x-3}{x-1} < - M[/itex] but it doesn't lead to the result [itex]1<x<1+\frac{2}{M+1}[/itex], what did I wrong ?

Thanks
 
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  • #2
You do understand that we can't tell you what you did wrong if you don't tell us what you did, don't you?
 
  • #3
I've set up this unequation [itex]\frac{x-3}{x-1} < - M[/itex] to prove the limit using its definition but it doesn't lead to the result [itex]1<x<1+\frac{2}{M+1}[/itex]
 
  • #4
scientifico said:
I've set up this unequation [itex]\frac{x-3}{x-1} < - M[/itex] to prove the limit using its definition but it doesn't lead to the result [itex]1<x<1+\frac{2}{M+1}[/itex]

Hint: ##M+3 = (M+1) + 2##.
 

Related to How can I use this hint to help prove the limit using the definition?

1. What is the definition of a limit in mathematical terms?

A limit is a concept in calculus that describes the behavior of a function as the input values approach a specific point, called the limit point. It is denoted by the symbol "lim" and is defined as the value that the function approaches as the input values get closer and closer to the limit point.

2. How is the limit of a function calculated using the definition?

The limit of a function can be calculated using the definition by evaluating the function at values closer and closer to the limit point and observing the trend of the output values. If the output values approach a specific value as the input values get closer to the limit point, then that value is considered as the limit of the function.

3. What is the purpose of using the definition to prove a limit?

The definition of a limit provides a rigorous and precise way of determining the limit of a function. It allows us to formally prove the existence and value of a limit and provides a solid foundation for further mathematical analysis and applications.

4. What are the key components of the limit definition?

The key components of the limit definition include the limit point, the function, and the limit value. The limit point is the point at which the input values are approaching, the function is the mathematical expression being evaluated, and the limit value is the value that the function approaches as the input values get closer to the limit point.

5. How does the limit definition differ from other methods of finding limits?

The limit definition is a more formal and rigorous approach to finding limits compared to other methods such as direct substitution or using algebraic manipulations. It provides a precise and unambiguous way of determining the limit of a function, whereas other methods may not always be applicable or may lead to incorrect results.

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