所屬科目:中山◆電機◆工程數學乙
1.Let x and y be nonzero vectors in Rn, n ≥ 2. Suppose x and y are not orthogonal, i.e. xTy ≠ 0. Let A = xyT. Which of the following statements are true? (A) O is an eigenvalue of A. (B) xTy is an eigenvalue of A. (C) x is an eigenvector of A. (D) The number of linearly independent eigenvectors associated with eigenvalue 0 is n - 1. (E) A is diagonalizable.
3.Consider the linear function L:R3 → R3. Suppose L(xi) = yi for i = 1,2,3,4, whereSuppose L(x4) = [c1, c2, c3]T. Which of the following statements are true? (A) c1= 1 (B)c1= 2 (C)c2=2 (D)c2=3(E)c3=-3
4.Let R( A ) denote the column space of A, and N( A ) denote the null space of A. Which of the following statements are true? (A) There exists a nonzero vector such that ATy = 0 and y = Ax for some (B) For every , we can always find some such that y = Ax. (C) Let p be the orthogonal projection of (D) Let y be a vector in (E) The intersection of R( A ) and N(AT) is the empty set.
5.Let E = {V1,V2,V3} be a basis for a three-dimensional subspace S of an inner product space V. Define. Suppose E is an orthogonal set with.Let Let p be the orthogonal projection of x onto y, and suppose p = ay, where a is a scalar. Which of the following statements are true? (A) (x,y) = 7 (B) (x,y) =8 (C) a = 7/33 (D) a = 8/14 (E) lIxll = 62
6.Let and nullity( A ) denote the dimension of N( A ). Suppose nullity( A ) = 2. Which of the following statements are true? (A) rank(AT) = 3 (B) nullity(AT) = 4 (C) Let A = [a1, a2, a3], where a1, a2, a3 are column vectors of A. Then a1 and a2 are linearly dependent. (D) The linear equation Ax = 0 has infinitely many solutions. (E) The linear equation ATy = d cannot have a unique solution for any.
8. Let and Let p be the orthogonal projection of b onto N( A ). Suppose b - p = av1 + βv2. Which of the following statements are true? (A)9a=8 (B) 9a= 9 (C) 9 β = 7 (D) 9 β=8 (E) 9a + 9 β = 15
9.Define a mapping L: R3 →R3 by L(x) = Kx, where . Suppose that E = {p, Kp, K2p} is an ordered basis of R3, and K3p - 5K2p + 7Kp - 11p = 0. Let A be the matrix representation of L with respect to basis E. SupposeWhich of the following statements are true? (A) (B)(C) (D)(E)
10. Let S be the transition matrix from {V1,V2} to {u1, u2}. Suppose Which of the following statements are true? (A)a=-1 (B)b= 2(C)c=3 (D)d=4 (E) a +b+c+d= 23
11.令。方程式的平衡點發生在 (A)(y1,y2)= (0,0) (B)(y1,y2)=(π,0) (C) 以上皆是
12.若μ>0,則初值在平衡點(y1,y2)=(0,0)附近的解會隨時間增加而 (A)收斂到(0,0)(B)遠離(0,0)(C)不一定,跟初值有關。
14.考慮對(y1,y2)=(π,0)作線性化之線性方程式此時,若μ<0,則該線性方程式之非零初值 解會隨時間增加而 (A)收斂到(0,0)(B)遠離(0,0)(C)不一定,跟初值有關。
15.考慮上題所述之線性方程式此時,若μ>0,則該線性方程式之非零初值解會隨時間增加而 (A)收斂到(0,0)(B)遠離(0,0)(C)不一定,跟初值有關。
下面16-20题為單選題,每题1分,總分5分。答錯或未作答者該題以0分計 考慮函數(R代表實数所成之集合)及Laplace轉换,定義為: 以下第16题到20题,我們令F(s)=L(f(t))。16.請問Laplace轉换是否為一個線性操作? (A)是(B)否(C)不一定,與函數f有關。
17.等於以下哪個函數? (A)(B) sF(s)(C)以上兩者都不是。
18.令θ>0為一實數,則L(f(t-θ))等於以下哪個函数? (A) F(s-θ) (B)(C) F(θs)
19.L(tf(t))等於以下哪個函數? (A) (B)sF(s) (C)
20.令n為一正整數,f(t)=tn,則L(f(t))等於以下哪個函數? (A) (B) (C)
(b).(5分)請問(a)小題的解是否滿足?
(c).(5分)令。請問此時微分方程 式的解是否滿足。
(d),(5分)今K=[k1 k2],w=KY带回原微分方程式,吾人得:。針對新的方 程式,請問是否存在k, k使得該方程式的任何「非零初值解」都滿足
(a).(5分)請問ω之值為何會讓解x(t)有最大振幅?
(b).(5分)請問ω之值為何會讓解x(t)與cos(ωt)恰好有π/4的相角差?