A* = |A|A^-1 = (1/3)A^-1 所以有 |(2A)^-1+3A*| = |(1/2)A^-1+A^-1| = | (3/2)A^-1| = (3/2)^3 |A^-1| = (27/8) * 3 = 81/8
