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Exercise 1.2.7 (Relatively prime and relatively prime by pairs)

Exhibit three integers that are relatively prime but not relatively prime in pairs.

Answers

Proof. 6 = 2 × 3 , 10 = 2 × 5 , 15 = 3 × 5 is such an example.

Then

gcd ( 6 , 10 , 15 ) = 1

(see Exercise 1.2.3(e) : − 14 × 6 + 7 × 10 + 1 × 15 = 1 ), but

gcd ( 6 , 10 ) = 2 , gcd ( 6 , 15 ) = 3 , gcd ( 10 , 15 ) = 5 .

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2024-06-16 11:05
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