r1. [4 paints} Let A be an n. X 11 matrix. H A is invertible, shew that A+A is invertible by nding a matrix C so that [HA + A} = [A + AK: 2 I. Nate: you may guess whet C is and then shew that it satisfies the inneribity eenditien, but please write deem: me guess that 5. [4 petite} You are running a enmputer ende with given n1atriees A, B, and C that are all size n x n and invertible. 1flan put the ende into a snbreutine to calculate the inverse of ABC, but the subroutine gives an errnr indicating the matrix yen gave it does nnt have an inverse. Show that the snbrnntine [written by surname else, net you} must be inee-rreet by showing that ABC is invertible by nding a matrix D set that (ARCH? = I and D(AHU} =