-4 -11 25 16. Without formally showing that there is a nontrivial linear combination of x-2x, x++x³ -1,x³+x+3, x-x2 - x, 10x - 91, 7x+ 3x- 7x2 equal to the zero polynomial, we can conclude these poly- nomials are linearly dependent. Why is this? if and

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Chapter7: Distance And Approximation
Section7.3: Least Squares Approximation
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On 2.4 number 16 show all work
In Exercises 13-15, find a basis for the subspace spanned
by the given vectors. (These do not have unique an-
2.4
Dimension; Nullspace, Row Space, and Column Space
105
b) Find a subset of pi(x), p2(x), p3(x), pa(x) that
-1
forms a basis for P2 in the manner of the proof
of part (2) of Lemma 2.11.
22. If the initial points of vectors in R' are placed at
11.
vectors.
3.
3
the origin, what geometric object is a subspace of
R of dimension one? What geometric object is a
-1
-1
2 0
subspace of R of dimension two?
23. Explain why the reduced row-echelon form of a ma-
1
1
-1 0
-2
12.
-2
1
trix is unique. Is the reduced column-echelon form
unique? Why or why not?
24. Use the system of linear equation solving capabili-
ties of Maple or another appropriate software pack-
age to show that the matrices
the given
swers.)
5
-6
13.
1-3
3
-7
-3 -33
13
11
-2
16 -2
1
17
-1
91
14.
-3 46
6 -98
32 -9
-1
-2 -1
2
21
5 -5
-4 0
15.
form a basis for M3×2(R).
25. Let A be the matrix
16. Without formally showing that there is a nontrivial
linear combination of x4-2x, x+x³ – 1, x³+x+3,
x - x² – x4, 10x – 91, ax4 + V3x³ - 7x2 equal
to the zero polynomial, we can conclude these poly-
nomials are linearly dependent. Why is this?
-2
3
-1
4
-2 7
3
-1
8
A =
1
7 -5 1
12:
0 12 -5 15 8
17. Show that det(A) +0 for an n x n matrix A if and
only if rank(A) = n.
a) In Maple, the command nullspace (or
equivalently, kernel) can be used to find a basis
for the nullspace of a matrix. (The basis vectors
will be given as row vectors instead of column
vectors.) Use this command or a corresponding
command in an appropriate software package to
find a basis for the nullspace of the matrix A.
K.
18. Suppose that A is an m x n matrix. Show that if
m > n, then the rows of A are linearly dependent.
atrix.
19. Suppose that A is an m x n matrix. Show that if
m < n, then the columns of A are linearly depen-
dent.
b) Bases for the row space of a matrix can be found
with Maple by using the gausselim or gaussjord
(or equivalently, rref) commands. Such bases
may also be found using the rowspace and
rowspan commands. Find bases for row space
of the matrix A using each of these four Maple
commands or corresponding commands in
another appropriate software package. If you
20. Consider the linearly independent polynomials
P1(x) =
X* + x, p2(x) = x + 1. Find a poly-
Lemma 2.11.
span P2.
2 21
Transcribed Image Text:In Exercises 13-15, find a basis for the subspace spanned by the given vectors. (These do not have unique an- 2.4 Dimension; Nullspace, Row Space, and Column Space 105 b) Find a subset of pi(x), p2(x), p3(x), pa(x) that -1 forms a basis for P2 in the manner of the proof of part (2) of Lemma 2.11. 22. If the initial points of vectors in R' are placed at 11. vectors. 3. 3 the origin, what geometric object is a subspace of R of dimension one? What geometric object is a -1 -1 2 0 subspace of R of dimension two? 23. Explain why the reduced row-echelon form of a ma- 1 1 -1 0 -2 12. -2 1 trix is unique. Is the reduced column-echelon form unique? Why or why not? 24. Use the system of linear equation solving capabili- ties of Maple or another appropriate software pack- age to show that the matrices the given swers.) 5 -6 13. 1-3 3 -7 -3 -33 13 11 -2 16 -2 1 17 -1 91 14. -3 46 6 -98 32 -9 -1 -2 -1 2 21 5 -5 -4 0 15. form a basis for M3×2(R). 25. Let A be the matrix 16. Without formally showing that there is a nontrivial linear combination of x4-2x, x+x³ – 1, x³+x+3, x - x² – x4, 10x – 91, ax4 + V3x³ - 7x2 equal to the zero polynomial, we can conclude these poly- nomials are linearly dependent. Why is this? -2 3 -1 4 -2 7 3 -1 8 A = 1 7 -5 1 12: 0 12 -5 15 8 17. Show that det(A) +0 for an n x n matrix A if and only if rank(A) = n. a) In Maple, the command nullspace (or equivalently, kernel) can be used to find a basis for the nullspace of a matrix. (The basis vectors will be given as row vectors instead of column vectors.) Use this command or a corresponding command in an appropriate software package to find a basis for the nullspace of the matrix A. K. 18. Suppose that A is an m x n matrix. Show that if m > n, then the rows of A are linearly dependent. atrix. 19. Suppose that A is an m x n matrix. Show that if m < n, then the columns of A are linearly depen- dent. b) Bases for the row space of a matrix can be found with Maple by using the gausselim or gaussjord (or equivalently, rref) commands. Such bases may also be found using the rowspace and rowspan commands. Find bases for row space of the matrix A using each of these four Maple commands or corresponding commands in another appropriate software package. If you 20. Consider the linearly independent polynomials P1(x) = X* + x, p2(x) = x + 1. Find a poly- Lemma 2.11. span P2. 2 21
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