9. (10%) Which of the following statements are true?
(A) Let A and B be n✖ n matrices. Assume that A is invertible and B3 = 0. If AB=BA, then A+B is also invertible.
(B) Let S be the set of all sequences in R which have exactly N non-zero elements where N is a known constant. S is a subspace of  R.
 
(C) Any square matrix A can be represented as a sum of a symmetric matrix and a skew-symmetric matrix.
 
(D) If A and B are similar, they have the same eigenvectors.

(E) If A, B6167c8d85aadf.jpg rank (A- B) ≤ rank( A )-rank( B )

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統計: A(3), B(1), C(0), D(1), E(1) #2789580