解答的第一步是先求逆矩阵 P^(-1)。可用行初等变换法。(P, E) =
[-1 1 1 1 0 0]
[ 1 0 2 0 1 0]
[ 1 1 -1 0 0 1]
行初等变换为
[ 1 -1 -1 -1 0 0]
[ 0 1 3 1 1 0]
[ 0 2 0 1 0 1]
行初等变换为
[ 1 0 -1 -1/2 0 1/2]
[ 0 1 0 1/2 0 1/2]
[ 0 0 3 1/2 1 -1/2]
行初等变换为
[ 1 0 0 -1/3 1/3 1/3]
[ 0 1 0 1/2 0 1/2]
[ 0 0 1 1/6 1/3 -1/6]
P^(-1) =
[-1/3 1/3 1/3]
[ 1/2 0 1/2]
[ 1/6 1/3 -1/6]
AP = P∧
A = P∧P^(-1),
A^2 = P∧P^(-1)P∧P^(-1) = P∧^2P^(-1)
A^3 = P∧P^(-1)P∧^2P^(-1) = P∧^3P^(-1)
φ(A) = A^3 + 2A^2 - 3A = P (∧^3 + 2∧^2 - 3∧) P^(-1)
= P diag(0, 10, 0) P^(-1) =
[5 0 5]
[0 0 0]
[5 0 5]