Definition 1. A square matrix A is called a diagonal matrix if all the off-diagonal entries of A are zero. That is, aij=0, wherever i=j. If the diagonal entries of A are a1,a2,,an, we write A=diag(a1,a2,an) (a) Let A be the diagonal matrix A=diag(2,4,1). Use Gauss-Jordan Elimination to find A1 (b) Suppose that A is an nn diagonal matrix with A=diag(a1,a2,an) and suppose that all the diagonal entries are non-zero. Generalize your work in part (a) to find a formula for A1, and prove that your formula is in fact the inverse matrix of A