Algebra: Proving (a^2,b^2)=1 Using GCD Proof

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SUMMARY

The discussion centers on proving that if the greatest common divisor (GCD) of two integers \(a\) and \(b\) is 1, then the GCD of their squares \(a^2\) and \(b^2\) is also 1. The proof utilizes a contradiction approach, assuming that \(gcd(a^2, b^2) = k\) where \(k > 1\). By considering a prime \(n\) that divides \(ab\), the proof demonstrates that \(n\) must divide either \(a\) or \(b\) but not both, leading to the conclusion that \(gcd(a^2, b^2) = 1\).

PREREQUISITES
  • Understanding of GCD (Greatest Common Divisor) concepts
  • Familiarity with prime numbers and their properties
  • Basic knowledge of proof techniques, particularly proof by contradiction
  • Elementary algebra, specifically properties of exponents
NEXT STEPS
  • Study the properties of GCD and how they apply to integer pairs
  • Learn about proof by contradiction and its applications in number theory
  • Explore the implications of prime factorization in GCD calculations
  • Investigate related theorems, such as Bézout's identity and its proof
USEFUL FOR

Mathematics students, educators, and anyone interested in number theory, particularly those studying GCD properties and proof techniques.

maphec
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(a,b)=d means d is the GCD of a and b

Question:

Let (a,b)=1

Prove: (a^2,b^2)=1



The hint that we were given is to prove this by contradiction ... but, I have no idea how to go about even starting this proof ... Any and all help would be greatly appreciated!
 
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Suppose that (a,b) = 1 and that (a2,b2) = k, where k > 1 ...
 
Proof:

Supposed n is prime and that n|ab
therefore, n|a or n|b, but not both

Case 1: n|a and n does not divide b
therefore n|a^2
since n does not divide b, n does not divide b^2

Case 2: n|b and n does not divide a
therefore n|b^2
since n does not divide a, n does not divide a^2

Thus, a^2 and b^2 have no common divisors
and therefore gcd(a^2,b^2)=1
 

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