11. Let H = {2k | ke Z}. Show that H ≤ Q*. 12. For N = 0, 1,2,... let NZ = {Nk | ke Z}. Prove that NZ ≤ Z and then show
Posted: Wed Jul 06, 2022 11:58 am
11. Let H = {2k | ke Z}. Show that H ≤ Q*. 12. For N = 0, 1,2,... let NZ = {Nk | ke Z}. Prove that NZ ≤ Z and then show that these are in fact the only subgroups of Z. 13. Let G be a group and H, K≤ G. Prove that HK and HUK are subgroups of G. 14. Let G be a group and show that Z(G) = {x € G | xg = gr for all g € G} I is a subgroup of G. We call Z(G) the center of G.