Chapter 5 Saddle point; direction of greatest attraction

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subject Authors David C. Lay

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page-pf1
Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
For the given matrix A, find a basis for the corresponding eigenspace for the given eigenvalue.
1)
A =1- 4 - 4
- 4 1 4
4- 4 - 7 , = -3
1)
A)
0
1
-1
B)
1
0
1, 0
1
-1
C)
1
0
-1, 0
1
1
D)
1
0
-1
Find the eigenvalues of A, and find a basis for each eigenspace.
2)
A =2 4
-4 2
2)
A)
2- 4i, 1
-i ; 2+ 4i, 1
i
B)
2- 4i, 1
i ; 2+ 4i, 1
-i
C)
2- 4i, 1 + 2i
-4 ; 2+ 4i, 1 - 2i
-4
D)
2- 4i, 1 - 2i
-4 ; 2+ 4i, 1 + 2i
-4
1
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Diagonalize the matrix A, if possible. That is, find an invertible matrix P and a diagonal matrix D such that A= PDP-1.
3)
A =
-8 0 0 0
0-8 0 0
1-4 8 0
-1 2 0 8
3)
A)
P =
16 32 0 0
8 8 0 0
1 0 1 0
0 1 0 1
, D =
-8 0 0 0
0-8 0 0
0 0 8 0
0 0 0 8
B)
Not diagonalizable
C)
P =
16 32 0 0
-8-8 0 0
1 0 1 0
0 1 0 1
, D =
8 0 0 0
0 8 0 0
0 0 -8 0
0 0 0 -8
D)
P =
16 -8 1 0
32 -8 0 0
0 0 1 0
0 0 0 1
, D =
8 0 0 0
0 8 0 0
0 0 -8 0
0 0 0 -8
Solve the initial value problem.
4)
x= Ax, x(0) =3
3.2 , where A =-4-3.125
8-4
4)
A)
x(t) =-2 sin 5t + 3 cos 5t
3.2 cos 5t + 4.8 sin 5t e-4t
B)
x(t) =2 sin 5t + -3 cos 5t
-3.2 cos 5t - 4.8 sin 5t e4t
C)
x(t) =-2 sin 5t + 3 cos 5t
3.2 cos 5t + 4.8 sin 5t e4t
D)
x(t) =2 sin 5t - 3 cos 5t
-3.2 cos 5t - 4.8 sin 5t e-4t
Consider the difference equation xk+1= Axk, where A has eigenvalues and corresponding eigenvectors v1, v2, and v3
given below. Find the general solution of this difference equation if x0 is given as below.
5)
1=1, 2=0.5, 3=0.4, v1=-6
6
1, v2=-3
1
-3, v3=1
-3
3, and x0=-47
29
3
5)
A)
xk=(1)kv1+ 5(0.5)kv2+ 4(0.4)kv3
B)
xk=(1)kv1+(0.5)kv2+(0.4)kv3
C)
xk=6(1)kv1+ 5(0.5)kv2+ 4(0.4)kv3
D)
xk=6(1)kv1+ 5(0.5)kv2+(0.4)kv3
2
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Find the characteristic equation of the given matrix.
6)
A =
2 5 3 1
0 4 -5 8
0 0 8 7
0 0 0 2
6)
A)
(2 -)2(4 -)(8-) = 0
B)
(2 -)(7-)(8-)(1-) = 0
C)
(2 -)(4-)(8-) = 0
D)
(2 -)(5-)(3-)(1-) = 0
The characteristic polynomial of a 5 × 5 matrix is given below. Find the eigenvalues and their multiplicities.
7)
5- 134- 93+ 4052
7)
A)
0 (multiplicity 2), 9 (multiplicity 2), -5 (multiplicity 1)
B)
0 (multiplicity 2), -9 (multiplicity 2), -5 (multiplicity 1)
C)
0 (multiplicity 2), -9 (multiplicity 2), 5 (multiplicity 1)
D)
0 (multiplicity 1), 9 (multiplicity 3), -5 (multiplicity 1)
Determine whether the origin is an attractor, repellor, or a saddle point of the dynamical system xk+1= Axk, where A is
given below. Determine the direction of greatest attraction or repulsion, appropriately.
8)
A =0.9 -0.4
0.5 1.110223025e-16
8)
A)
Saddle point; direction of greatest attraction: along the line through 0 and -4
-5, direction of
greatest repulsion: along the line through 0 and 1
1
B)
Attractor; direction of greatest attraction: along the line through 0 and -4
-5
C)
Repellor; direction of greatest repulsion: along the line through 0 and 1
1
D)
Attractor; direction of greatest attraction: along the line through 0 and 1
1
3
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For the given matrix and eigenvalue, find an eigenvector corresponding to the eigenvalue.
9)
A =-24 -14
84 46 , =4
9)
A)
1
-2
B)
1
46
C)
-2
1
D)
1
0
Determine whether the origin is an attractor, repellor, or a saddle point of the dynamical system xk+1= Axk, where A is
given below. Determine the direction of greatest attraction or repulsion, appropriately.
10)
A =5.0 0
01.2
10)
A)
Attractor; direction of greatest attraction: along the line through 0 and 1
0
B)
Attractor; direction of greatest repulsion: along the line through 0 and 0
1
C)
Saddle point; direction of greatest attraction: along the line through 0 and 1
0, direction of
greatest repulsion: along the line through 0 and 0
1
D)
Repellor; direction of greatest repulsion: along the line through 0 and 1
0
Apply the power method to the matrix A below with x0=0
1. Stop when k = 5, and determine the dominant eigenvalue
and corresponding eigenvector.
11)
A =-56 -15
220 59
11)
A)
4, 1
-4
B)
-1, 1
-4
C)
4, -3
11
D)
-1, -3
11
4
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Find the matrix of the linear transformation T: V
W relative to B and C.
12)
Suppose B = {b1, b2} is a basis for V and C = {c1, c2, c3} is a basis for W. Let T be defined by
T(b1) = -5c1- 6c2+ 5c3
T(b2) = -5c1- 12c2+ 2c3
12)
A)
-5-6 5
0 6 3
B)
-5-6 5
-5-12 2
C)
-5-5
-6-12
D)
-5 0
-6-6
For the given matrix A, find a basis for the corresponding eigenspace for the given eigenvalue.
13)
A =-4 0 0
2-6 0
-8-16 2, = -4
13)
A)
1
-1
-4
B)
1
1
0, 1
0
-4
C)
1
1
4
D)
1
1
0, 1
0
4
Find the eigenvalues of the given matrix.
14)
85 16
-440 -83
14)
A)
-3, 5
B)
5
C)
3, -5
D)
3
5
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Use the inverse power method to determine the smallest eigenvalue of the matrix A.
15)
Assume that the eigenvalues are roughly 0.8, 2.6, and 16.
A =1 0 0
-0.75 1.75 0.75
-0.75 0.75 4.25
15)
A)
2.5
B)
1
C)
6
D)
0.8
Define T: R2
R2 by T(x) = Ax, where A is the matrix defined below. Find the requested basis B for R2 and the
corresponding B-matrix for T.
16)
Find a basis B for R2 and the B-matrix D for T with the property that D is a diagonal matrix.
A =-67 -60
72 65
16)
A)
B =1
5, -1
6, D =-7 0
0 5
B)
B =1
-1, 5
6, D =-7 0
0 5
C)
B =1
-1, 5
-6, D =-7 0
0 5
D)
B =5
-6, 1
-1, D =-7 0
0 5
6
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Determine whether the origin is an attractor, repellor, or a saddle point of the dynamical system xk+1= Axk, where A is
given below. Determine the direction of greatest attraction or repulsion, appropriately.
17)
A =11 -7
10.5 -6.5
17)
A)
Saddle point; direction of greatest attraction: along the line through 0 and 1
1, direction of
greatest repulsion: along the line through 0 and -2
-3
B)
Saddle point; direction of greatest attraction: along the line through 0 and 2
3, direction of
greatest repulsion: along the line through 0 and 1
1
C)
Attractor; direction of greatest attraction: along the line through 0 and 1
1
D)
Repellor; direction of greatest repulsion: along the line through 0 and 2
3
Define T: R2
R2 by T(x) = Ax, where A is the matrix defined below. Find the requested basis B for R2 and the
corresponding B-matrix for T.
18)
Find a basis B for R2 and the B-matrix D for T with the property that D is an upper triangular
matrix.
A =-232 -1156
49 244
18)
A)
B =34
-5, -7
1, D =6 1
0 6
B)
B =34
7, 5
1, D =-6 1
0-6
C)
B =34
-7, -5
1, D =6 1
0 7
D)
B =34
-7, -5
1, D =6 1
0 6
7
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Diagonalize the matrix A, if possible. That is, find an invertible matrix P and a diagonal matrix D such that A= PDP-1.
19)
A =6 0 0
1 6 0
0 0 6
19)
A)
P =1 0 0
6 6 0
0 1 1 , D =6 1 0
0 6 0
0 0 6
B)
Not diagonalizable
C)
P =1 6 1
0 6 1
-1 0 1 , D =6 0 0
0 6 0
0 0 6
D)
P =1 0 -1
6 6 0
1 1 1 , D =6 0 1
1 6 1
0 0 6
Find the eigenvalues of the given matrix.
20)
0-1
2 3
20)
A)
1, -2
B)
-2
C)
1
D)
1, 2
Find the matrix of the linear transformation T: V
W relative to B and C.
21)
Suppose B = {b1, b2, b3} is a basis for V and C = {c1, c2} is a basis for W. Let T be defined by
T(b1) =5c1+c2
T(b2) =6c1- 6c2
T(b3) =5c1- 6c2
21)
A)
5 1
6-6
5-6
B)
6 0 -1
1-6-6
C)
5 6
6 0
5-1
D)
5 6 5
1-6-6
8
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Diagonalize the matrix A, if possible. That is, find an invertible matrix P and a diagonal matrix D such that A= PDP-1.
22)
A =
-3 0 0 0
0-3 0 0
- 12 3-912
0 0 0 -3
22)
A)
P =
2 0 -2 1
0 2 1 0
1 0 0 1
0 0 1 0
, D =
-3 0 0 0
0-3 0 0
0 0 -3 0
0 0 0 -9
B)
P =
4-2 1 0
8-2 0 0
1 0 1 1
0 1 1 0
, D =
-3 0 0 0
0-3 0 0
0 0 -9 0
0 0 0 -9
C)
Not diagonalizable
D)
P =
2 0 1 0
0 2 0 0
-2 1 0 1
1 0 1 0
, D =
-3 0 0 0
0-3 0 0
0 0 -3 0
0 0 0 -9
Find a formula for Ak, given that A = PDP-1, where P and D are given below.
23)
A =5 3
-210 , P =3 1
2 1 , D =7 0
0 8
23)
A)
7k 0
0 8k
B)
3·7k+2·8k3·8k+3·7k
2·7k+2·8k3·8k+2·7k
C)
3·7k- 2 ·8k3·8k+3·7k
2·7k+2·8k3·8k-2·7k
D)
3·7k- 2 ·8k3·8k-3·7k
2·7k-2·8k3·8k-2·7k
The characteristic polynomial of a 5 × 5 matrix is given below. Find the eigenvalues and their multiplicities.
24)
5+ 174+ 723
24)
A)
0 (multiplicity 3), 8 (multiplicity 1), 9 (multiplicity 1)
B)
0 (multiplicity 1), -9 (multiplicity 1), -8 (multiplicity 1)
C)
0 (multiplicity 1), 8 (multiplicity 1), 9 (multiplicity 1)
D)
0 (multiplicity 3), -9 (multiplicity 1), -8 (multiplicity 1)
9
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Diagonalize the matrix A, if possible. That is, find an invertible matrix P and a diagonal matrix D such that A= PDP-1.
25)
A =1 1 4
0-4 0
-5-1-8
25)
A)
P =1 0 -1
-9-4 0
1 1 1 , D =-4 0 0
0-4 0
0 0 -3
B)
P =1 0 -1
-9-4 0
1 1 1 , D =-4 0 -3
0-4 0
0-4-3
C)
P =1 0 -1
0-4 0
1 1 1 , D =-4 0 0
0 1 0
0 0 -3
D)
P =1-9-1
-9-4 0
1-4 1 , D =-4 1 0
0-4 0
0 0 -3
Find the eigenvalues of A, and find a basis for each eigenspace.
26)
A =0.76 -1.04
0.64 0.44
26)
A)
-0.6 + 0.8i, 1 + 5i
4 ; -0.6 - 0.8i, 1 - 5i
4
B)
0.6 + 0.8i, 1 - 5i
4 ; 0.6 - 0.8i, 1 + 5i
4
C)
0.6 - 0.8i, 1 - 5i
4 ; 0.6 + 0.8i, 1 + 5i
4
D)
-0.6 - 0.8i, 1 + 5i
4 ; -0.6 + 0.8i, 1 - 5i
4
For the given matrix and eigenvalue, find an eigenvector corresponding to the eigenvalue.
27)
A =32 -9
108 -31 , =5
27)
A)
3
1
B)
1
-3
C)
1
3
D)
-3
1
10
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Find the characteristic equation of the given matrix.
28)
A =
1-7 4 9
0-5 7 -1
0 0 -7 5
0 0 0 6
28)
A)
(1 -)(-5-)(-7-)(6-) = 0
B)
(1 -)(-7-)(4-)(9-) = 0
C)
(6 -)(5-)(-1-)(9-) = 0
D)
(9 -)(-1-)(5-)(6-) = 0
Apply the power method to the matrix A below with x0=0
1. Stop when k = 5, and determine the dominant eigenvalue
and corresponding eigenvector.
29)
A =-7-3
4 0
29)
A)
-4, 1
-1
B)
-3, 3
-4
C)
-4, 3
-4
D)
-3, 1
-1
11
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Answer Key
Testname: C5
12

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