To show that , take any element on the left side and show that it's also an element of the right side. An element of the left side is for some . And since , ...
I am stuck on the following problem:
If C is a subgroup of an abelian group G, then a*H = H*a for all a in G.
I know that I have to prove
1.) a*H is a subset of H*a
2.) H*a is a subset of a*H
After this, I really don't know how to go about it. Thanks for any and all help.