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Unformatted text preview: a h4 ig6 e k# 6 i b iC a aha 2.4 Problem 25 ( a ): (4) = 2. ( b ): (10) = 4. ( c ): (13) = 12. 2.4 Problem 26: If n is prime then it is relatively prime to all the numbers 1 , 2 , 3 , . . ., ( n 1), so ( n ) = n 1. If n = 1 then (1) = 1 negationslash = 1 1. If n is not prime and n > 1 then it has some factor a < n , and gcd( a, n ) = a negationslash = 1. Thus one of the numbers 1 , 2 , 3 , . . ., ( n 1) is not relatively prime to n , and ( n ) negationslash = n 1. 2.4 Problem 27: If p is prime then the only prime factor of p k is p . Thus the only numbers that are not relatively prime to p k are the numbers that have p as a factor. The numbers less than or equal to p k that are not relatively prime to p k are the numbers p, 2 p, 3 p, 4 p, . . ., p k , and there are p k 1 of these. Thus ( p k ) = p k p k 1 . 2.4 Problem 30 ( a ): lcm(2 2 3 3 5 5 , 2 5 3 3 5 2 ) = 2 5 3 3 5 5 . ( b ): lcm(2 3 5 7 11 13 , 2 11 3 9 11 17 14 ) = 2 11 3 9 5 7 11 13 17 14 . ( c ): lcm(17 , 17 17 ) = 17 17 . ( d ): lcm(2 2 7 , 5 3 13) = 2 2 5 3 7 13. ( e ): lcm(0 , 5) is undefined. (It cant be 0, because the LCM is defined as a positive integer.) However, some texts would define it to be 0 in this case. ( f ): lcm(2 3 5 7 , 2 3 5 7) = 2 3 5 7....
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This note was uploaded on 07/12/2008 for the course MAT 243 taught by Professor Callahan during the Spring '06 term at ASU.
 Spring '06
 CALLAHAN

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