Homepage Solution manuals David S. Dummit Abstract Algebra Exercise 3.2.1 (First application of Lagrange's Theorem)

Exercise 3.2.1 (First application of Lagrange's Theorem)

Which of the following are permissible orders for subgroups of order 120 : 1 , 2 , 5 , 9 , 15 , 60 , 240 ? For each permissible order give the corresponding index.

Answers

Proof. By Lagrange’s Theorem, the cardinal of a subgroup H of G must divide | G | = 120 , so the permissible orders for subgroups H among 1 , 2 , 5 , 9 , 15 , 60 , 240 are 1 , 2 , 5 , 15 , 60 , whose respective indices ( G : H ) are 120 , 60 , 24 , 8 , 2 .

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2025-12-06 12:10
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