Past exam of the mathematics course of the University of Cambridge / 2021 / ia / Paper 3 / 8D / a / i

Table of contents
- Solution i

Solution

Identify

A

with

{(a, 1) : a \in A}

. Componentwise use of the stated multiplication shows that this set contains the identity and is closed under products and inverses, so it is a subgroup. It has the two cosets

A, A (e, - 1),

and therefore has index two. Every index-two subgroup is normal, so

A ◃ D (A) .

 Ancestors (11)

 View article source

 Discussion (0)

There are no discussions about this article yet.

 Articles by others on the same topic (0)

There are currently no matching articles.

  See all articles in the same topic Create my own version