Let A = -1 -2 -5 -7 1 1] 1 1 0 1 -1 42 -3 2 6 (a) Find the value of a for which v = (a, 1, 2, 2) is an eigenvector. What is the eigenvalue corresponding v in this case? (b) Show that v is also an eigenvector of A. What is its corresponding eigenvalue? [3] [2]