Show that for all integers n>2, n does not divide n^2+2

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In summary, the conversation discusses how to prove that for all integers n>2, n does not divide n^2+2. One suggested solution is to use induction, but the exact recursive phrasing is not clear. Another suggestion is to use the fact that n divides n^2, but it is not clear how to apply it in this problem. Finally, it is proposed to use the assumption that n divides n^2+2 and reach a contradiction, proving that n does not actually divide n^2+2.
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numba
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Homework Statement


Show that for all integers n>2, n does not divide n^2+2.

2. The attempt at a solution
I believe this solution can be solved by induction, I just don't know how to phrase it recursively.

For all n>2, n^2+2 mod n ≠ 0

Base case n=3
3^2 + 2 =11
11 mod 3 = 2 ≠ 0.

Show that
(n-1)^2 +2 mod n-1 ≠ 0
 
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  • #2
I don't think induction is the right way to do this. n divides n2, can you use that in this problem?
 
  • #3
I can use that, but I'm not sure how it would be done. Intuitively it makes sense, but is there an axiom that I could use that proves this?
 
  • #4
Suppose n does divide n2+ 2. Then there exist integer m such that mn= n2+ 2. Now divide both sides by n.
 

1. Why is it important to prove that n does not divide n^2+2 for all integers n>2?

Proving this statement is important because it helps to understand the properties of divisibility and the relationship between numbers. It also serves as a fundamental concept in number theory and other areas of mathematics.

2. How can we prove that n does not divide n^2+2 for all integers n>2?

We can prove this statement by contradiction. Assume that there exists an integer n>2 such that n divides n^2+2. Then, n^2+2 = nk for some integer k. Rearranging, we get n^2-nk+2 = 0. This is a quadratic equation in n, and by solving for n, we can show that there are no integer solutions, contradicting our assumption.

3. Can we use mathematical induction to prove this statement?

Yes, we can use mathematical induction to prove this statement. The base case, n=3, can be verified manually. Then, assuming the statement holds for some integer k>2, we can show that it also holds for k+1 by using the fact that k does not divide k^2+2 and the algebraic manipulation from question 2.

4. What are the consequences if we cannot prove that n does not divide n^2+2 for all integers n>2?

If we cannot prove this statement, it would mean that there exists at least one integer n>2 such that n divides n^2+2. This would have significant implications in number theory and other areas of mathematics, as it would challenge our understanding of divisibility and the properties of integers.

5. Are there any real-life applications of this statement?

While this statement may not have direct real-life applications, the concept of divisibility and the techniques used to prove it are important in many fields, such as computer science, cryptography, and data encryption. Additionally, understanding this statement can lead to a deeper understanding of number theory, which has numerous practical applications in various industries.

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