13. (5%) Consider the matrix Which of the following values of c will make the matrix A invertible?
(A) 3；
(B) 4；
(C) 5；
(D) 6；
(E) None of the above.

9. (5%) An undamped string/mass system, in which the mass m = 1 slug and the spring constant k = 10 lb/t, is driven by the 2-periodic external force F(t) = 1-t,0 ＜t＜2； f(t+2) = f(t). Assume that when f(t) is extended to the negative t-axis in a periodic manner, the resulting function is odd. Find a particular solution Xp(t).(A) p(t)=nπt, (B)s=nπ, (C) k=nπ, (D) k=n2n2, (E) s=n2n2,

複選題10. (5%) Please pick the statements below that are true. (A) The rank of the coefficient mnatrix of a consistent system of linear equations is equal to the ariables in the genera number of basic varia ral solution of the system. (B) The matrix-vector product of an m X n matrix A and a' vector in Rn is a linear combination of the columns of A. (C) A subset of Rn containing fewer than n vectors must be linearly independent. (D) If S1 and S2 are finite subsets of R" having equal spans, then S1and S2 contain the same number of vectors. (E) If the columns of an n X n matrix A for a generating set of Rn, then the reduced row echelon form of A is In.

複選題11. (5%) Please pick the statements below that are true. (A) If A and B are m x n matrices and C is an n X p matrix, then (A + B)C = AC + BC. (B) For any matrices A and B, if A is the inverse of BT, then A is the transpose of B-I. (C) An n x n matrix is invertible if and only if its rows are linearly independent. (D) The codomain of any function is contained in its range. (E) for every standard vector e；, then f(v) mg(v) for every v in Rn.

複選題12. (5%) Please pick the statements below that are true. (A) A function is onto if its range equals its domain. (B) A linear transformation is one-to-one if and only if every vector in its range is the image of a unique vector in its domain. (C) For any m X n matrices A and B and any scalars c and d, (CA + dB)T = cAT + dBT. (D) No scaling operations are required in the forward pass of Gaussian elimination. (E) If A and B are invertible n X n matrices, then A + B is invertible.

14. (5%) Which of the following subsets of Rnis a subspace? (A) (B) (C) (D) (E)

複選題15. (5%) Which of the following statements are correct? (A) A basis for a subspace is a linearly independent subset of the subspace that is as large as possible. (B) If V is a subspace of dimension k, then every generating set for V contains exactly k vectors. (C) is any basis for Rn, then there exists a vector v so that v can not be expressed as a linear combination of bi, ba...., bn. (D) Let T be a linear operator on Rn, and u and V be two bases forRn. Denote [T]Bas the representative matrix of T with respect to any basis B for Rn. Then, [T]u and [T]v are similar. (E) If B is a basis for Rn and T is the identity operator on R", then [T]B = In.

複選題16. (5%) Which of the following statements are correct? (A) If λ is an eigenvalue of an n x n matrix A, then for any (B) If there exists some such that Av =λv, then λ is an eigenvalue of A. (C) If two matrices have the same characteristic polynomials, then they have the same eigen- values. (D) A diagonal matrix is always diagonalizable. (E) Let A and P be n X n matrices. If the columins of P form a set of n linearly independent eigenvectors of A, then AP is a diagonal matrix. 

1. Dr. Sun was one of the ______ physicians s in his generation. (A) forbearing (B) foremost (C) forerunner (D) foreseen

2. Her husband was always tired after doing such an ______ task. (A) intriguing (B) obvious (C) envious (D) arduous

3. Some people think that video games have a(n) ______ influence on children. (A) inhibiting (B) boring (C) educated (D) pernicious