Prove Limit of Sequence: (n+6)/(n^2-6)=0

In summary, the goal is to prove that the limit of (n+6)/(n^2-6) as n approaches infinity is equal to 0. This requires showing that for any given epsilon, there exists a value N such that for all n greater than or equal to N, the expression (n+6)/(n^2-6) is less than epsilon. This can be achieved by setting N to be the maximum of 3 and 1/epsilon, and using the fact that n+6 is always smaller than n for n greater than or equal to 3, and n^2-6 is always larger than n^2 for n greater than or equal to 1.
  • #1
torquerotates
207
0

Homework Statement


prove Lim(n->infinity) (n+6)/(n^(2)-6)=0



Homework Equations



lim{a}=a for n->infinity

For any epslion>0 there is a N>0 such that n>N => |{a}-a|<epslion

The Attempt at a Solution



For n>or=3, |(n+6)/(n^(2)-6)|<epslion becomes( dropping the absolute value sign) (n+6)/(n^(2)-6)< epslion

But n+6<n and n^(2)-6>or equal (1/3)n^(2)

so 3/n=n/((1/3)n^(2))<(n+6)/(n^(2)-6)<epslion

both n>or=3 and n>3/epslion implies that I make N=Max(3,3/epslion)

Is this correct? The book had a different way of doing it but since there are many ways of proving things, the book's solution doesn't help.
 
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  • #2
torquerotates said:
But n+6<n

 
  • #3
lol ok. ( fixing it)

For n>or=3, |(n+6)/(n^(2)-6)|<epslion becomes( dropping the absolute value sign) (n+6)/(n^(2)-6)< epslion

But n+6>n and n^(2)-6< n^(2)

so 1/(n)=n/(n^(2))<(n+6)/(n^(2)-6)<epslion

both n>or=3 and n>1/epslion implies that I make N=Max(3,1/epslion)

how about now?
 

1. What is a limit of a sequence?

A limit of a sequence is a value that the terms of the sequence approach as the index (n) goes to infinity.

2. How do you prove the limit of a sequence?

To prove the limit of a sequence, we must show that for any given value of epsilon (>0), there exists a positive integer N such that for all n>N, the absolute value of (n+6)/(n^2-6) is less than epsilon.

3. Can you use algebraic manipulation to prove the limit of a sequence?

Yes, algebraic manipulation can be used to prove the limit of a sequence. In this case, we can use the properties of limits and algebraic rules to simplify the expression (n+6)/(n^2-6) into a form that is easier to analyze.

4. Why is it important to prove the limit of a sequence?

Proving the limit of a sequence is important because it allows us to understand the behavior of the sequence as the index (n) approaches infinity. It also helps us to determine if the sequence is convergent or divergent, which has significant implications in various fields of mathematics and science.

5. Are there any special techniques for proving the limit of a sequence?

Yes, there are special techniques for proving the limit of a sequence, such as the Squeeze Theorem, the Monotone Convergence Theorem, and the Cauchy Criterion. These techniques can be used in certain cases to simplify the proof and provide a more elegant solution.

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