Evaluate this limit, introductory real analysis

In summary, the problem is finding the limit of the sequence [xn] = (-3n^2 + n + 1) / (n^2 - 2n + 3), using the definition of a limit and the squeeze principle. The attempt at a solution involved factoring out a variable of the highest power and manipulating the expression to cancel out terms. The final method used was to divide both the numerator and denominator by n^2, and then applying the squeeze theorem to find the limit. However, the use of 1/n going to zero in a sequence was not allowed in this problem.
  • #1
jaqueh
57
0

Homework Statement


limit of the sequence, [xn]=(-3n2+n+1)/(n2-2n+3)


Homework Equations


I so far know about the definition of a limit, squeeze principle, and lim[xnyn] = 0 if xn or yn goes to 0


The Attempt at a Solution


Tried the definition of the limit but the algebra got really crazy so i don't think I'm supposed to do it that way. I'm trying to squeeze it between (-3n2/n2) and (-3n3)/(n3), but i don't know if i can prove that the cubed one is greater than my sequence
 
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  • #2
Try factoring out a variable of the highest power. This is a standard method for problems like these before l'Hospital's rule is introduced.

Edit: Just in case you aren't allowed to use that method..

If you want to use the squeeze theorem and then the definition of the limit, you need to factor out some terms by manipulating the original expression so they cancel out.
 
Last edited:
  • #3
ah I've divided the numerator by 3 but am still stuck. I know it hits -3.

yeah I'm trying to see what I can make the expression into so things will start cancellong
 
  • #4
Did you misunderstand what scurty said? Nothing about dividing by -3: factor out, or, same thing, divide both numerator and denominator by [itex]n^2[/itex].
 
  • #5
ok great I have it now. I do that then squeeze because I'm not allowed to say yet that 1/n goes to zero in a sequence I think
 

What is a limit in introductory real analysis?

A limit in introductory real analysis is a fundamental concept in mathematics that describes the behavior of a function as its input approaches a certain value. It is used to determine the value that a function approaches as its input gets closer and closer to a specific value, but may not necessarily reach that value.

How do you evaluate a limit in introductory real analysis?

To evaluate a limit in introductory real analysis, you must first determine the value that the function approaches as its input gets closer and closer to the given value. This can be done by plugging in values that are approaching the given value from both sides and seeing if the function approaches the same value, or by using limit laws and algebraic manipulation to simplify the expression.

What are the common techniques used to evaluate limits in introductory real analysis?

There are several common techniques used to evaluate limits in introductory real analysis, including direct substitution, factoring, rationalization, and using L'Hospital's rule. These techniques are used to manipulate the expression and simplify it in order to determine the limit.

What are the key concepts to keep in mind when evaluating limits in introductory real analysis?

When evaluating limits in introductory real analysis, it is important to keep in mind the properties of limits, such as the limit laws and the Squeeze Theorem. It is also important to consider the behavior of the function as the input approaches the given value, and to be aware of any potential indeterminate forms that may require further simplification.

Why are limits important in introductory real analysis?

Limits are important in introductory real analysis because they allow us to understand the behavior of a function near a specific value, even if the function is not defined at that value. They are essential in determining continuity, differentiability, and other important properties of functions in mathematics and other fields of science.

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