Can a group of order 98 have a subgroup of order 7?

  • Context: Graduate 
  • Thread starter Thread starter rayveldkamp
  • Start date Start date
Click For Summary
SUMMARY

A group of order 98 must contain a subgroup of order 7 due to Cauchy's theorem, which states that if a prime divides the order of a group, then the group contains an element of that order. In this case, since 7 is prime and divides 98, there exists an element of order 7, generating a subgroup of order 7. Additionally, Sylow's theorems confirm the existence of subgroups of any prime power order that divides the group's order, reinforcing the conclusion that a Sylow-7-subgroup exists.

PREREQUISITES
  • Understanding of group theory concepts, specifically Sylow's theorems.
  • Familiarity with Cauchy's theorem in the context of group orders.
  • Knowledge of prime factorization and its implications in group orders.
  • Basic concepts of subgroup generation and element orders in groups.
NEXT STEPS
  • Study Sylow's theorems in detail, focusing on their applications in group theory.
  • Explore Cauchy's theorem and its implications for group elements and orders.
  • Investigate examples of groups of various orders to see how subgroup structures manifest.
  • Learn about the classification of finite groups and the significance of subgroup orders.
USEFUL FOR

This discussion is beneficial for students and researchers in abstract algebra, particularly those studying group theory, as well as mathematicians interested in subgroup structures and their properties.

rayveldkamp
Messages
60
Reaction score
0
Hi
Why must a group of order 98 contain a subgroup of order 7?
I would think that Sylow's 1st theorem implies there exists at least one Sylow-7-subgroup of order 49 and at least one Sylow-2-subgroup of order 2 (since 98=2x7x7).
Thanks

Ray Veldkamp
 
Physics news on Phys.org
7 is prime, 7 divides 98, hence by Cauchy's theorem there is an element of order 7. The subgroup generated by this element is of order 7.
 
or because the stronger version of sylows theorems say there is always a subgroup of any prime power order that divides the order of the group, not just the maximal prime power order.
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
5K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 1 ·
Replies
1
Views
4K
  • · Replies 2 ·
Replies
2
Views
3K