19. Let H and K be subgroups of a group G, where H = 9, 1K1 =12 and where the index [G:HNK] =IGI. Find (HNKI.
Problem 3. Subgroups of quotient groups. Let G be a group and let H<G be a normal subgroup. Let K be a subgroup of G that contains H. (1) Show that there is a well-defined injective homomorphism i: K/ H G /H given by i(kH) = kH. By abuse of notation, we regard K/H as being the subgroup Imi < G/H consisting of all cosets of the form KH with k EK. (2) Show that every subgroup of G/H is...
Let G be a group and let H,K be normal subgroups of G such that H∩K = {e} and that G = {hk|h ∈ H,k ∈ K}. (1)Prove that for every h∈H, k∈K we have kh(k^-1)(h^−1) = e in G. (2) Prove that the group G is isomorphic to H × K. Hint: For (2), consider the map φ : H ×K → G, defined as φ(h,k) = hk, whereh ∈ H,k ∈ K.
19. Let G be a group with no nontrivial proper subgroups. (a) Show that G must be cyclic. (b) What can you say about the order of G?
(8) Let G be a group and let H be a subgroup of G. Prove that the right cosets of H partition G, that is, G= U Hy HYEH\G and, if y, y' E G and Hyn Hy' + 0, then Hy= Hy'.
Let G be a group of order 231 = 3 · 7 · 11. Let H, K and N
denote sylow 3,7 and 11-subgroups of G, respectively.
a) Prove that K, N are both proper subsets of G.
b) Prove that G = HKN.
c) Prove that N ≤ Z(G). (you may find below problem useful).
a): <|/ is a normal subgroup, i.e. K,N are normal subgroups
of G
(below problem): Let G be a group, with H ≤ G...
Let G be a finite group, and let H be a subgroup of order n.
Suppose that H is the only subgroup of order n. Show that H is
normal in G. [consider the subgroup
of G]
aha а
Let G be a finite group and let H be a subgroup of G. Show using double cosets that there is a subset T of G which is simultaneously a left transversal for H and a right transversal for H.
10. Let G = D. be the dihedral group on the octagon and let N = (r) be the subgroup of G generated by r4. (a) Prove that N is a normal subgroup of G. (b) If G =D3/N, find G. (c) Using the bar notation for cosets, show that G = {e, F, 2, 3, 5, 87, 82, 83}. Hint: Show that the RHS consists of distinct elements and then use part (b). (d) Prove that G-D4. Hint: It...
6. Let G be a p-group and H be a proper subgroup of G. Then (1) Show that N[H]# H. (5 pts) (2) Show that N(H) is not simple. (5 pts)