Assucalive. 9. show that {1, 2, 3} under multiplication modulo 4 1s not a group but that {1, 2, 3, 4} under multiplication modulo 5 is a group. 10. q no. 10&11

assucalive. 9. Show that {1, 2, 3} under multiplication modulo 4 1s not a group but that {1, 2, 3, 4} under multiplication modulo 5 is a group. 10. Show that the group GL(2, R) of Example 9 is non-Abelian by ex- hibiting a pair of matrices A and B in GL2, R) such that AB # BA. 2 6 3 5 11. Find the inverse of the element in GL(2, Z,).