1. othf] IICR}. o b I :11: 1 b memo in 1H1H 1 i {b} Show that a matrix A in (IL-31:13} is in the on: i bgroup if and only:r ii: A{L} '5; L. {That is, for any 1urector 1| in L, 211' is also in L.) {c} 'Forget the 15' and View the top coordinate of the multiplication [matrix] times [vector] in part {a} as the function It > on? + b. Show that the product {of two matrices} in the :13 + 1: group corresponds to composition of the corresponding functions