Find bases for N(T) and R(T) and verify the Dimension Theorem
$begingroup$
$Tpmatrix{a11&a12&a13\a21&a22&a23\a31&a32&a33}$= $pmatrix{a11+a12+a13&a21+a22+a23\a21+a22+a23&0}$
I know what the Dimension Theorem is and by looking at the equation I can tell that a11+a12=-a13 and so on shows that the null space contains more than just the zero vector, however I struggle in figuring out how to express the bases of N(T) and R(T).
linear-algebra
$endgroup$
add a comment |
$begingroup$
$Tpmatrix{a11&a12&a13\a21&a22&a23\a31&a32&a33}$= $pmatrix{a11+a12+a13&a21+a22+a23\a21+a22+a23&0}$
I know what the Dimension Theorem is and by looking at the equation I can tell that a11+a12=-a13 and so on shows that the null space contains more than just the zero vector, however I struggle in figuring out how to express the bases of N(T) and R(T).
linear-algebra
$endgroup$
3
$begingroup$
It should not be hard to find some elements of the range, and then to prove that those elements are linearly independent and span the range. Try it!
$endgroup$
– Gerry Myerson
Dec 8 '13 at 2:54
add a comment |
$begingroup$
$Tpmatrix{a11&a12&a13\a21&a22&a23\a31&a32&a33}$= $pmatrix{a11+a12+a13&a21+a22+a23\a21+a22+a23&0}$
I know what the Dimension Theorem is and by looking at the equation I can tell that a11+a12=-a13 and so on shows that the null space contains more than just the zero vector, however I struggle in figuring out how to express the bases of N(T) and R(T).
linear-algebra
$endgroup$
$Tpmatrix{a11&a12&a13\a21&a22&a23\a31&a32&a33}$= $pmatrix{a11+a12+a13&a21+a22+a23\a21+a22+a23&0}$
I know what the Dimension Theorem is and by looking at the equation I can tell that a11+a12=-a13 and so on shows that the null space contains more than just the zero vector, however I struggle in figuring out how to express the bases of N(T) and R(T).
linear-algebra
linear-algebra
asked Dec 8 '13 at 2:52
user114220user114220
59117
59117
3
$begingroup$
It should not be hard to find some elements of the range, and then to prove that those elements are linearly independent and span the range. Try it!
$endgroup$
– Gerry Myerson
Dec 8 '13 at 2:54
add a comment |
3
$begingroup$
It should not be hard to find some elements of the range, and then to prove that those elements are linearly independent and span the range. Try it!
$endgroup$
– Gerry Myerson
Dec 8 '13 at 2:54
3
3
$begingroup$
It should not be hard to find some elements of the range, and then to prove that those elements are linearly independent and span the range. Try it!
$endgroup$
– Gerry Myerson
Dec 8 '13 at 2:54
$begingroup$
It should not be hard to find some elements of the range, and then to prove that those elements are linearly independent and span the range. Try it!
$endgroup$
– Gerry Myerson
Dec 8 '13 at 2:54
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
You can just try some small numbers, easiest to play with $1$ and $0$.
For $N(T)$, as you started you get these $3$ equations ($2$ of them are the same) as $-a_{11}-a_{12} =a_{13}$, so that $a_{11}$, $a_{12}$ and $a_{21}$, $a_{22}$ can be anything, only $a_{13}$ and $a_{23}$ are bound to them. Also, $a_{31}, a_{32}, a_{33}$ can be anything.
So, consider these elements of $N(T)$:
- $a_{11}=1$, rest is $0$ ($implies a_{13}=-1$)
- $a_{12}=1$, rest is $0$ ($implies a_{13}=-1$)
- $a_{21}=1$, rest is $0$ ($implies a_{23}=-1$)
- and so on...
$endgroup$
add a comment |
$begingroup$
quite sure:
basis for $N(T) = $$pmatrix{1&0&-1\0&0&0\0&0&0}$
$pmatrix{0&1&-1\0&0&0\0&0&0}$$pmatrix{0&0&0\1&0&-1\0&0&0}$$pmatrix{0&0&0\0&1&-1\0&0&0}$$pmatrix{0&0&0\0&0&0\1&0&0}$$pmatrix{0&0&0\0&0&0\0&1&0}$$pmatrix{0&0&0\0&0&0\0&0&1}$
basis for $R(T) = pmatrix{1&0\0&0},pmatrix{0&1\1&0}$
edit: I think this is what Berci said
$endgroup$
$begingroup$
Yes, almost. I just haven't found my 'matrix' switch on the keyboard :) The last two ones of $N(T)$ are not correct, $a_{31}, a_{32}, a_{33}$ are free.
$endgroup$
– Berci
Dec 8 '13 at 3:24
$begingroup$
ah, you're right!
$endgroup$
– Sam Creamer
Dec 8 '13 at 3:36
1
$begingroup$
Did you notice that every matrix in the range is symmetric?
$endgroup$
– Gerry Myerson
Dec 8 '13 at 3:39
$begingroup$
I corrected according to the comments.
$endgroup$
– Berci
Dec 8 '13 at 12:44
add a comment |
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2 Answers
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2 Answers
2
active
oldest
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$begingroup$
You can just try some small numbers, easiest to play with $1$ and $0$.
For $N(T)$, as you started you get these $3$ equations ($2$ of them are the same) as $-a_{11}-a_{12} =a_{13}$, so that $a_{11}$, $a_{12}$ and $a_{21}$, $a_{22}$ can be anything, only $a_{13}$ and $a_{23}$ are bound to them. Also, $a_{31}, a_{32}, a_{33}$ can be anything.
So, consider these elements of $N(T)$:
- $a_{11}=1$, rest is $0$ ($implies a_{13}=-1$)
- $a_{12}=1$, rest is $0$ ($implies a_{13}=-1$)
- $a_{21}=1$, rest is $0$ ($implies a_{23}=-1$)
- and so on...
$endgroup$
add a comment |
$begingroup$
You can just try some small numbers, easiest to play with $1$ and $0$.
For $N(T)$, as you started you get these $3$ equations ($2$ of them are the same) as $-a_{11}-a_{12} =a_{13}$, so that $a_{11}$, $a_{12}$ and $a_{21}$, $a_{22}$ can be anything, only $a_{13}$ and $a_{23}$ are bound to them. Also, $a_{31}, a_{32}, a_{33}$ can be anything.
So, consider these elements of $N(T)$:
- $a_{11}=1$, rest is $0$ ($implies a_{13}=-1$)
- $a_{12}=1$, rest is $0$ ($implies a_{13}=-1$)
- $a_{21}=1$, rest is $0$ ($implies a_{23}=-1$)
- and so on...
$endgroup$
add a comment |
$begingroup$
You can just try some small numbers, easiest to play with $1$ and $0$.
For $N(T)$, as you started you get these $3$ equations ($2$ of them are the same) as $-a_{11}-a_{12} =a_{13}$, so that $a_{11}$, $a_{12}$ and $a_{21}$, $a_{22}$ can be anything, only $a_{13}$ and $a_{23}$ are bound to them. Also, $a_{31}, a_{32}, a_{33}$ can be anything.
So, consider these elements of $N(T)$:
- $a_{11}=1$, rest is $0$ ($implies a_{13}=-1$)
- $a_{12}=1$, rest is $0$ ($implies a_{13}=-1$)
- $a_{21}=1$, rest is $0$ ($implies a_{23}=-1$)
- and so on...
$endgroup$
You can just try some small numbers, easiest to play with $1$ and $0$.
For $N(T)$, as you started you get these $3$ equations ($2$ of them are the same) as $-a_{11}-a_{12} =a_{13}$, so that $a_{11}$, $a_{12}$ and $a_{21}$, $a_{22}$ can be anything, only $a_{13}$ and $a_{23}$ are bound to them. Also, $a_{31}, a_{32}, a_{33}$ can be anything.
So, consider these elements of $N(T)$:
- $a_{11}=1$, rest is $0$ ($implies a_{13}=-1$)
- $a_{12}=1$, rest is $0$ ($implies a_{13}=-1$)
- $a_{21}=1$, rest is $0$ ($implies a_{23}=-1$)
- and so on...
edited Dec 8 '13 at 3:26
answered Dec 8 '13 at 3:11


BerciBerci
61.7k23674
61.7k23674
add a comment |
add a comment |
$begingroup$
quite sure:
basis for $N(T) = $$pmatrix{1&0&-1\0&0&0\0&0&0}$
$pmatrix{0&1&-1\0&0&0\0&0&0}$$pmatrix{0&0&0\1&0&-1\0&0&0}$$pmatrix{0&0&0\0&1&-1\0&0&0}$$pmatrix{0&0&0\0&0&0\1&0&0}$$pmatrix{0&0&0\0&0&0\0&1&0}$$pmatrix{0&0&0\0&0&0\0&0&1}$
basis for $R(T) = pmatrix{1&0\0&0},pmatrix{0&1\1&0}$
edit: I think this is what Berci said
$endgroup$
$begingroup$
Yes, almost. I just haven't found my 'matrix' switch on the keyboard :) The last two ones of $N(T)$ are not correct, $a_{31}, a_{32}, a_{33}$ are free.
$endgroup$
– Berci
Dec 8 '13 at 3:24
$begingroup$
ah, you're right!
$endgroup$
– Sam Creamer
Dec 8 '13 at 3:36
1
$begingroup$
Did you notice that every matrix in the range is symmetric?
$endgroup$
– Gerry Myerson
Dec 8 '13 at 3:39
$begingroup$
I corrected according to the comments.
$endgroup$
– Berci
Dec 8 '13 at 12:44
add a comment |
$begingroup$
quite sure:
basis for $N(T) = $$pmatrix{1&0&-1\0&0&0\0&0&0}$
$pmatrix{0&1&-1\0&0&0\0&0&0}$$pmatrix{0&0&0\1&0&-1\0&0&0}$$pmatrix{0&0&0\0&1&-1\0&0&0}$$pmatrix{0&0&0\0&0&0\1&0&0}$$pmatrix{0&0&0\0&0&0\0&1&0}$$pmatrix{0&0&0\0&0&0\0&0&1}$
basis for $R(T) = pmatrix{1&0\0&0},pmatrix{0&1\1&0}$
edit: I think this is what Berci said
$endgroup$
$begingroup$
Yes, almost. I just haven't found my 'matrix' switch on the keyboard :) The last two ones of $N(T)$ are not correct, $a_{31}, a_{32}, a_{33}$ are free.
$endgroup$
– Berci
Dec 8 '13 at 3:24
$begingroup$
ah, you're right!
$endgroup$
– Sam Creamer
Dec 8 '13 at 3:36
1
$begingroup$
Did you notice that every matrix in the range is symmetric?
$endgroup$
– Gerry Myerson
Dec 8 '13 at 3:39
$begingroup$
I corrected according to the comments.
$endgroup$
– Berci
Dec 8 '13 at 12:44
add a comment |
$begingroup$
quite sure:
basis for $N(T) = $$pmatrix{1&0&-1\0&0&0\0&0&0}$
$pmatrix{0&1&-1\0&0&0\0&0&0}$$pmatrix{0&0&0\1&0&-1\0&0&0}$$pmatrix{0&0&0\0&1&-1\0&0&0}$$pmatrix{0&0&0\0&0&0\1&0&0}$$pmatrix{0&0&0\0&0&0\0&1&0}$$pmatrix{0&0&0\0&0&0\0&0&1}$
basis for $R(T) = pmatrix{1&0\0&0},pmatrix{0&1\1&0}$
edit: I think this is what Berci said
$endgroup$
quite sure:
basis for $N(T) = $$pmatrix{1&0&-1\0&0&0\0&0&0}$
$pmatrix{0&1&-1\0&0&0\0&0&0}$$pmatrix{0&0&0\1&0&-1\0&0&0}$$pmatrix{0&0&0\0&1&-1\0&0&0}$$pmatrix{0&0&0\0&0&0\1&0&0}$$pmatrix{0&0&0\0&0&0\0&1&0}$$pmatrix{0&0&0\0&0&0\0&0&1}$
basis for $R(T) = pmatrix{1&0\0&0},pmatrix{0&1\1&0}$
edit: I think this is what Berci said
edited Dec 8 '13 at 12:44


Berci
61.7k23674
61.7k23674
answered Dec 8 '13 at 3:20


Sam CreamerSam Creamer
209414
209414
$begingroup$
Yes, almost. I just haven't found my 'matrix' switch on the keyboard :) The last two ones of $N(T)$ are not correct, $a_{31}, a_{32}, a_{33}$ are free.
$endgroup$
– Berci
Dec 8 '13 at 3:24
$begingroup$
ah, you're right!
$endgroup$
– Sam Creamer
Dec 8 '13 at 3:36
1
$begingroup$
Did you notice that every matrix in the range is symmetric?
$endgroup$
– Gerry Myerson
Dec 8 '13 at 3:39
$begingroup$
I corrected according to the comments.
$endgroup$
– Berci
Dec 8 '13 at 12:44
add a comment |
$begingroup$
Yes, almost. I just haven't found my 'matrix' switch on the keyboard :) The last two ones of $N(T)$ are not correct, $a_{31}, a_{32}, a_{33}$ are free.
$endgroup$
– Berci
Dec 8 '13 at 3:24
$begingroup$
ah, you're right!
$endgroup$
– Sam Creamer
Dec 8 '13 at 3:36
1
$begingroup$
Did you notice that every matrix in the range is symmetric?
$endgroup$
– Gerry Myerson
Dec 8 '13 at 3:39
$begingroup$
I corrected according to the comments.
$endgroup$
– Berci
Dec 8 '13 at 12:44
$begingroup$
Yes, almost. I just haven't found my 'matrix' switch on the keyboard :) The last two ones of $N(T)$ are not correct, $a_{31}, a_{32}, a_{33}$ are free.
$endgroup$
– Berci
Dec 8 '13 at 3:24
$begingroup$
Yes, almost. I just haven't found my 'matrix' switch on the keyboard :) The last two ones of $N(T)$ are not correct, $a_{31}, a_{32}, a_{33}$ are free.
$endgroup$
– Berci
Dec 8 '13 at 3:24
$begingroup$
ah, you're right!
$endgroup$
– Sam Creamer
Dec 8 '13 at 3:36
$begingroup$
ah, you're right!
$endgroup$
– Sam Creamer
Dec 8 '13 at 3:36
1
1
$begingroup$
Did you notice that every matrix in the range is symmetric?
$endgroup$
– Gerry Myerson
Dec 8 '13 at 3:39
$begingroup$
Did you notice that every matrix in the range is symmetric?
$endgroup$
– Gerry Myerson
Dec 8 '13 at 3:39
$begingroup$
I corrected according to the comments.
$endgroup$
– Berci
Dec 8 '13 at 12:44
$begingroup$
I corrected according to the comments.
$endgroup$
– Berci
Dec 8 '13 at 12:44
add a comment |
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$begingroup$
It should not be hard to find some elements of the range, and then to prove that those elements are linearly independent and span the range. Try it!
$endgroup$
– Gerry Myerson
Dec 8 '13 at 2:54