help!GR 9367 # 59

Forum for the GRE subject test in mathematics.
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sss
Posts: 6
Joined: Sun Oct 07, 2012 5:17 pm

help!GR 9367 # 59

Post by sss » Sun Oct 07, 2012 5:21 pm

GR 9367 # 59
Two subgroups H and K of a group have orders 12 and 30, respectively. Which of the following could Not be the order of the subgroup of G generated by H and K?
answer: A 30
I couldn't figure it out.
Thank you very much in advance!

vonLipwig
Posts: 52
Joined: Sat Mar 17, 2012 9:58 am

Re: help!GR 9367 # 59

Post by vonLipwig » Sun Oct 07, 2012 6:23 pm

The subgroup H of order 12 is going to be a subgroup of the subgroup generated by H and K, so 12 must divide the order of this second subgroup. 12 doesn't divide 30.

sss
Posts: 6
Joined: Sun Oct 07, 2012 5:17 pm

Re: help!GR 9367 # 59

Post by sss » Sun Oct 07, 2012 9:06 pm

Thank you very much~



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