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Homework Help: Cyclic subgroups of an Abelian group

  1. Jan 29, 2009 #1
    1. The problem statement, all variables and given/known data
    If G is an Abelian group and contains cyclic subgroups of orders 4 and 6, what other sizes of cyclic subgroups must G contain?


    2. Relevant equations
    A cyclic group of order n has cyclic subgroups with orders corresponding to all of n's divisors.


    3. The attempt at a solution
    I know that a cyclic group of order n has cyclic subgroups with orders corresponding to all of n's divisors, so I'm inclined to say that G must have cyclic subgroups with orders 1, 2, and 3. But I also have a hunch that the subgroups of orders 4 and 6 combine in some way, so maybe there's also a cyclic subgroup of order lcm(4,6) = 12? Am I on the right track here?
     
  2. jcsd
  3. Jan 29, 2009 #2
    Yes you are. Since 4 and 6 divide n, so must 12. (Think of the prime factorization of n).
     
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