Number Theory Problem: Proving (a,b)=1 if a|c and b|c

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SUMMARY

The discussion centers on proving that if two integers \( a \) and \( b \) are coprime, and both divide a third integer \( c \), then their product \( ab \) also divides \( c \). The proof utilizes the properties of coprime integers and their prime factorizations. Specifically, it leverages the relationship \( ax + by = 1 \) for integers \( x \) and \( y \) to establish that \( c \) can be expressed in terms of \( a \) and \( b \), confirming that \( ab \) divides \( c \).

PREREQUISITES
  • Understanding of integer divisibility (e.g., \( a|c \) means \( c \) is divisible by \( a \))
  • Familiarity with the concept of coprime integers (e.g., \( (a,b)=1 \))
  • Basic knowledge of prime factorization and its implications
  • Experience with linear combinations of integers (e.g., \( ax + by = 1 \))
NEXT STEPS
  • Study the properties of coprime integers and their implications in number theory
  • Learn about the Fundamental Theorem of Arithmetic and prime factorization
  • Explore linear Diophantine equations and their solutions
  • Investigate applications of divisibility in modular arithmetic
USEFUL FOR

Students of number theory, mathematicians interested in integer properties, and educators teaching divisibility concepts in mathematics.

yeland404
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Homework Statement



a,b,c belong to Z with (a,b)=1. Prove that if a|c and b|c, then ab|c

Homework Equations


let a1,a2...an, c belong to Zwith a1...an pairwise relatively prime, prove if ai|c for each i, then a1a2...an|c


The Attempt at a Solution



if a|c, then c=ea, b|c, then c=fb, then which the next step and how it relates with (a,b)=1
 
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(a,b)=1, thus consider the prime factorization of e.
 
There exists integers x, y such that ax+by=1. Therefore c=acx+bcy=abrx+basy.
 

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