Solution to Abstract Algebra by Dummit & Foote 3rd edition Chapter 3.2 Exercise 3.2.11
Solution: See Lemma 3 of Exercise 3.2.10.
Subgroup index is multiplicative across intermediate subgroups
Blog
Solution to Abstract Algebra by Dummit & Foote 3rd edition Chapter 3.2 Exercise 3.2.11
Solution: See Lemma 3 of Exercise 3.2.10.