Divisors of a Number: n2+1 for 4k+1 Divisibility

  • Thread starter Thread starter jeedoubts
  • Start date Start date
AI Thread Summary
The discussion centers on the divisors of the number N = (7^n1)(9^n2)(11^n1) and specifically addresses the condition when n1 is even. It is established that the total number of divisors of the form 4k+1 must be divisible by n2 + 1. The participants analyze the factorization of N, noting that the use of 9 instead of 3 is significant for determining the divisors. There is a suggestion to explore the powers of 9, which fit the 4k+1 form, while also proving that such numbers cannot be multiples of 7 or 11. The conversation emphasizes the mathematical relationships and properties of divisors in this context.
jeedoubts
Messages
16
Reaction score
0
1. Homework Statement
let N= (7^n1)(9^n2)(11^n1)
if n1 is even,then the total number of divisors of the form of 4k+1 must be divisible by?

correct answer is n2+1

3. The Attempt at a Solution
total number of divisors = (n1+1)(n2+1)(n1+1)
 
Last edited:
Physics news on Phys.org
jeedoubts said:
1. Homework Statement
let N= (7^n1)(9^n2)(11^n1)
if n1 is even,then the total number of divisors of the form of 4k+1 must be divisible by?

correct answer is n2+1

3. The Attempt at a Solution
total number of divisors = (n1+1)(n2+1)(n1+1)

can anybody please help me uot in this question?
 
jeedoubts said:
1. Homework Statement
let N= (7^n1)(9^n2)(11^n1)
if n1 is even,then the total number of divisors of the form of 4k+1 must be divisible by?

correct answer is n2+1

3. The Attempt at a Solution
total number of divisors = (n1+1)(n2+1)(n1+1)

can anybody please help me out in this question?
 
Hm... I don't have the solution, but can give some idea: The factor decomposition is funny, using 9 instead of 3. Anyway, put it like 9^n2 (7*11)^n1. Now get numbers of the form 4k+1: 1, 5, 9, 13, 17, 21, 25... 81... So, you see: powers of 9 are of the form 4k+1. You have to prove that no number of that form can be a multiple of 7 or 11.
 
I picked up this problem from the Schaum's series book titled "College Mathematics" by Ayres/Schmidt. It is a solved problem in the book. But what surprised me was that the solution to this problem was given in one line without any explanation. I could, therefore, not understand how the given one-line solution was reached. The one-line solution in the book says: The equation is ##x \cos{\omega} +y \sin{\omega} - 5 = 0##, ##\omega## being the parameter. From my side, the only thing I could...
Back
Top