複選題

三、Which of the following properties of eigenvalue is/are true?
(A) A scalar λ is an eigenvalue of matrix A if and only if λ is an eigenvalue of .
(B) A matrix is positive semi-definite if and only if all of its eigenvalues are non-negative.
(C) Every eigenvalue of a matrix A is also an eigenvalue of A².
(D) If matrices A and B are similar, then they have the same eigenvalues.
(E) None of the above are true.

49.假設美國投資人看好我國股市前景,對台灣投資資金 5000 萬美元, 請問在台幣/美元的外匯市場上會發生何種變動? (A) 外匯的供給曲線右移。  (B)匯率不變。 (C)台幣相對於美元會貶值。(D) 美元相對於台幣升值。 (E) 外匯的需求曲線左移。

50.財政部開放外國人投資台灣的股市, 將外國人投資每家上市公司的上 限由 25% 提高到 50 %, 此舉造成外資大量湧入台灣股市； 在其它條件不變 下(中央銀行亦未干預), (A) 市場利率將大跌。 (B)股市泡沫將造成房地產 大跌價。 (C)新台幣將因此貶值。(D) 市場利率將大漲。(E) 新台幣將因 此升值。  

一、 Which of the following sets is basis (are bases) for ? (A) .(B) (C) (D) (E)None of the above are true.

複選題二、 Which of the following statements about the multiplicative inverse of a matrix is/are true?(A) A matrix A is called invertible if there exists a matrix B such that AB is an identitymatrix.(B) If a matrix is both diagonalizable and invertible, then so is its multiplicative inverse.(C) Suppose that matrices A of size n x n and D of size m x m are invertible and thatmatrix C is of size m X fi； then the following identity is true(D) Methods for finding the multiplicative inverse of a matrix include LU factorization,Gaussian elimination, eigen-decomposition, and Gram-Schmidt process.(E) None of the above are true.

四 、 Which of the following matrices is/are diagonalizable? (A) (B) (C) (D) (E) None of the above are true. 

複選題五、Which of the following statements about matrix factorization is/are true? (A) If a matrix A is positive definite, then A has "an" LU factorization, A = LU, where the diagonal entries of U are positive.(B) Suppose that a matrix A = QR, where Q is an m x n matrix and R is an n X n matrix. If the columns of A are linearly independent, then R must be invertible.(C) Any factorization of a matrix A = , with matrices U, V square and positive diagonal entries in the matrix D, is called a singular value decomposition of A.(D) An n x n matrix A is positive definite if and only if A has "a" Cholesky factorization A = for some invertible upper triangular matrix R whose diagonal entries are all positive.(E) None of the above are true.

複選題六、 The Householder matrix H = is the orthogonalprojection matrix onto some nonzero vector , is a reflection matrix. Which of thefollowing statements is/are true?(A) Consider the 2-dimensional space, ie. n = 2. For vectors u, d, p,q   shown in thefigure below, we have H d = p.(B) H is a symmetric and orthogonal matrix.(C) Both linear systems A z = o and HAz = Ho are equivalent.(D) Let a = ≠0. Then llull2 = -2 llαll u1and Hα = (E) None of the above are true.

七、 Given029which of the following statements is/are true?(A) (B) (C) (D) det(F) = 20.(E) None of the above are true.

八、 Consider a 3 x 3 nonzero matrix A, and let W = . The leastsquares solutions xLs to Ax = b are illustrated in the following figure，where projwe b is theorthogonal projection of vector b onto vector space W. A minimun length least squares, solution EMurs is the one among the least squares solutions that has a minimum norm.Which of the following stateme ents is/are true?(A)(B) (C) (D) The minimum length least squares solution EMLLS to Ax = b is unique, and =projvxLs, where V = .(E) None of the above are true.

九 、 Let v1 and v2 be the eigenvectors of matrix A corresponding respectively to eigenvalues λ1 and λ2, where  It is found that λ1 > 1 > |λ2l. With matrix A, ,be a series of vectors related by . Given the initial condition x0 = = , which of the following statements is/are true? (A)(B)(C) (D) (E) None of the above are true.