2. Let A =
0........ −1..........1.......k
2...........0....... −1.......1
2........k + 1......−1......1
2...........0...........k......1
, where k is a scalar.
(a) By reducing A to a row echelon form with elementary row operations, express det(A) in terms of k.
(b) For what value(s) of k is the matrix A singular?