Chapter 4 - Section 4.3 - Primes and Greatest Common Divisors - Exercises - Page 272: 16

a) yes b) no c) yes d) yes

a)21 and 34 are co-primes 34 and 55 are co-primes 55 and 21 are co-primes b) 85/17=5 c)25 and 41 are co-primes 25 and 49 are co-primes 25 and 64 are co-primes 41 and 49 are co-primes 41 and 64 are co-primes 49 and 64 are co-primes d) c)17 and 18 are co-primes 17 and 19 are co-primes 17 and 23 are co-primes 18 and 19 are co-primes 18 and 23 are co-primes 19 and 23 are co-primes