解: f(A) = 2E+3A+A^2
=
2 0 0
0 2 0
0 0 2
+
3 -6 6
9 6 3
0 3 -3
-5 -4 -2
9 -1 7
3 1 2
0 -10 4
18 7 10
3 4 1