Give an example,with justification,of a group G with subgroups H and K such that HK is not a subgroup of G.?
1 Answer
Feb 25, 2018
Here's an example...
Explanation:
Let
Let
Let
Then:
#HK = { a^m b^n | m, n in ZZ }#
#ab in HK#
#(ab)^(-1) = b^(-1) a^(-1) !in HK#