设A为n阶矩阵,且满足方程3A^-2A+4I=0.证明A与3A+2I均可逆

由已知,A(3A-2E) = -4I所以A可逆,且 A^-1 = (-1/4)(A-2E).再由 3A^-2A+4I=0得 A(3A+2I) - (4/3)(3A+2I) +8/3 I = 0所以 (A-(4/3)I)(3A+2I) = - 8/3 I所以 3A+2I 可逆,且 (3A+2I)^-1 = (-3/8) (A-(4/3)I)....