Complete ${(2,3,1),(1,4,3)}$ to a basis of $Bbb R^3$
Having the following set: $C = {(2,3,1),(1,4,3)}$ I want to be able to generate; $V = mathbb{R}^3$
Since $V = mathbb{R}^3$ has dimension $3$, $C$ also needs to have dimension $3$, however, how do I find the vector I need to add to $C$ in order to be able to generate $V$?
Is sufficient to have 3 vectors that are Linearly Independent and then I can generate $V$? And how do I find it?
Thank you!
linear-algebra vector-spaces cross-product
add a comment |
Having the following set: $C = {(2,3,1),(1,4,3)}$ I want to be able to generate; $V = mathbb{R}^3$
Since $V = mathbb{R}^3$ has dimension $3$, $C$ also needs to have dimension $3$, however, how do I find the vector I need to add to $C$ in order to be able to generate $V$?
Is sufficient to have 3 vectors that are Linearly Independent and then I can generate $V$? And how do I find it?
Thank you!
linear-algebra vector-spaces cross-product
add a comment |
Having the following set: $C = {(2,3,1),(1,4,3)}$ I want to be able to generate; $V = mathbb{R}^3$
Since $V = mathbb{R}^3$ has dimension $3$, $C$ also needs to have dimension $3$, however, how do I find the vector I need to add to $C$ in order to be able to generate $V$?
Is sufficient to have 3 vectors that are Linearly Independent and then I can generate $V$? And how do I find it?
Thank you!
linear-algebra vector-spaces cross-product
Having the following set: $C = {(2,3,1),(1,4,3)}$ I want to be able to generate; $V = mathbb{R}^3$
Since $V = mathbb{R}^3$ has dimension $3$, $C$ also needs to have dimension $3$, however, how do I find the vector I need to add to $C$ in order to be able to generate $V$?
Is sufficient to have 3 vectors that are Linearly Independent and then I can generate $V$? And how do I find it?
Thank you!
linear-algebra vector-spaces cross-product
linear-algebra vector-spaces cross-product
edited Dec 29 '18 at 12:00
Asaf Karagila♦
301k32425755
301k32425755
asked Dec 28 '18 at 16:23
Miguel Ferreira
664
664
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4 Answers
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Take any vector $(a,b,c)$ which is not a linear combination of $(2,3,1)$ and $(1,4,3)$. For instance $(1,0,0)$ will do. In fact, any vector $(a,b,c)$ such that $bneq a+c$ will do.
add a comment |
This method works in the general case and does not require using the "cross product":
Let $C=(v_1,v_2)$ as in the question. Choose any basis of $mathbb{R}^3$. For simplicity we shall take $e_1,e_2,e_3$. Then look at
$(v_1,v_2,e_1)$, $(v_1,v_2,e_2)$ and $(v_1,v_2,e_3)$.
One of them is necessarily a linearly independent sequence of vectors (this can be checked by hand, for example you can take $e_1$ as in Jose' answer).
Indeed, if by contradiction all of them were linearly dependent then since $v_1,v_2$ are independent $e_1,e_2,e_3 in text{Span} {v_1,v_2}$. But this would mean that $mathbb{R}^3 = text{Span} {v_1,v_2}$ which is impossible.
Thank you very much for the help!
– Miguel Ferreira
Dec 28 '18 at 17:16
add a comment |
HINT
If you have 3 linearly independent vectors, they will span all of $mathbb{R}^3$ (why?).
To get a third one, easiest way is to construct one perpendicular to them both, which is to take a cross product of the two you have
Thank you for the help!:)
– Miguel Ferreira
Dec 28 '18 at 17:10
add a comment |
Just take the cross product:
$$(2,3,1) times (1,4,3) = (5,-5,5)$$
Then ${(2,3,1),(1,4,3),(5,-5,5)}$ is linearly independent and hence a basis for $mathbb{R}^3$.
Thank you for the help! Didn't know about this method :)
– Miguel Ferreira
Dec 28 '18 at 17:17
add a comment |
Your Answer
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4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
Take any vector $(a,b,c)$ which is not a linear combination of $(2,3,1)$ and $(1,4,3)$. For instance $(1,0,0)$ will do. In fact, any vector $(a,b,c)$ such that $bneq a+c$ will do.
add a comment |
Take any vector $(a,b,c)$ which is not a linear combination of $(2,3,1)$ and $(1,4,3)$. For instance $(1,0,0)$ will do. In fact, any vector $(a,b,c)$ such that $bneq a+c$ will do.
add a comment |
Take any vector $(a,b,c)$ which is not a linear combination of $(2,3,1)$ and $(1,4,3)$. For instance $(1,0,0)$ will do. In fact, any vector $(a,b,c)$ such that $bneq a+c$ will do.
Take any vector $(a,b,c)$ which is not a linear combination of $(2,3,1)$ and $(1,4,3)$. For instance $(1,0,0)$ will do. In fact, any vector $(a,b,c)$ such that $bneq a+c$ will do.
edited 2 days ago
answered Dec 28 '18 at 16:27
José Carlos Santos
150k22121221
150k22121221
add a comment |
add a comment |
This method works in the general case and does not require using the "cross product":
Let $C=(v_1,v_2)$ as in the question. Choose any basis of $mathbb{R}^3$. For simplicity we shall take $e_1,e_2,e_3$. Then look at
$(v_1,v_2,e_1)$, $(v_1,v_2,e_2)$ and $(v_1,v_2,e_3)$.
One of them is necessarily a linearly independent sequence of vectors (this can be checked by hand, for example you can take $e_1$ as in Jose' answer).
Indeed, if by contradiction all of them were linearly dependent then since $v_1,v_2$ are independent $e_1,e_2,e_3 in text{Span} {v_1,v_2}$. But this would mean that $mathbb{R}^3 = text{Span} {v_1,v_2}$ which is impossible.
Thank you very much for the help!
– Miguel Ferreira
Dec 28 '18 at 17:16
add a comment |
This method works in the general case and does not require using the "cross product":
Let $C=(v_1,v_2)$ as in the question. Choose any basis of $mathbb{R}^3$. For simplicity we shall take $e_1,e_2,e_3$. Then look at
$(v_1,v_2,e_1)$, $(v_1,v_2,e_2)$ and $(v_1,v_2,e_3)$.
One of them is necessarily a linearly independent sequence of vectors (this can be checked by hand, for example you can take $e_1$ as in Jose' answer).
Indeed, if by contradiction all of them were linearly dependent then since $v_1,v_2$ are independent $e_1,e_2,e_3 in text{Span} {v_1,v_2}$. But this would mean that $mathbb{R}^3 = text{Span} {v_1,v_2}$ which is impossible.
Thank you very much for the help!
– Miguel Ferreira
Dec 28 '18 at 17:16
add a comment |
This method works in the general case and does not require using the "cross product":
Let $C=(v_1,v_2)$ as in the question. Choose any basis of $mathbb{R}^3$. For simplicity we shall take $e_1,e_2,e_3$. Then look at
$(v_1,v_2,e_1)$, $(v_1,v_2,e_2)$ and $(v_1,v_2,e_3)$.
One of them is necessarily a linearly independent sequence of vectors (this can be checked by hand, for example you can take $e_1$ as in Jose' answer).
Indeed, if by contradiction all of them were linearly dependent then since $v_1,v_2$ are independent $e_1,e_2,e_3 in text{Span} {v_1,v_2}$. But this would mean that $mathbb{R}^3 = text{Span} {v_1,v_2}$ which is impossible.
This method works in the general case and does not require using the "cross product":
Let $C=(v_1,v_2)$ as in the question. Choose any basis of $mathbb{R}^3$. For simplicity we shall take $e_1,e_2,e_3$. Then look at
$(v_1,v_2,e_1)$, $(v_1,v_2,e_2)$ and $(v_1,v_2,e_3)$.
One of them is necessarily a linearly independent sequence of vectors (this can be checked by hand, for example you can take $e_1$ as in Jose' answer).
Indeed, if by contradiction all of them were linearly dependent then since $v_1,v_2$ are independent $e_1,e_2,e_3 in text{Span} {v_1,v_2}$. But this would mean that $mathbb{R}^3 = text{Span} {v_1,v_2}$ which is impossible.
edited Dec 28 '18 at 19:26
answered Dec 28 '18 at 16:36
Yanko
6,124724
6,124724
Thank you very much for the help!
– Miguel Ferreira
Dec 28 '18 at 17:16
add a comment |
Thank you very much for the help!
– Miguel Ferreira
Dec 28 '18 at 17:16
Thank you very much for the help!
– Miguel Ferreira
Dec 28 '18 at 17:16
Thank you very much for the help!
– Miguel Ferreira
Dec 28 '18 at 17:16
add a comment |
HINT
If you have 3 linearly independent vectors, they will span all of $mathbb{R}^3$ (why?).
To get a third one, easiest way is to construct one perpendicular to them both, which is to take a cross product of the two you have
Thank you for the help!:)
– Miguel Ferreira
Dec 28 '18 at 17:10
add a comment |
HINT
If you have 3 linearly independent vectors, they will span all of $mathbb{R}^3$ (why?).
To get a third one, easiest way is to construct one perpendicular to them both, which is to take a cross product of the two you have
Thank you for the help!:)
– Miguel Ferreira
Dec 28 '18 at 17:10
add a comment |
HINT
If you have 3 linearly independent vectors, they will span all of $mathbb{R}^3$ (why?).
To get a third one, easiest way is to construct one perpendicular to them both, which is to take a cross product of the two you have
HINT
If you have 3 linearly independent vectors, they will span all of $mathbb{R}^3$ (why?).
To get a third one, easiest way is to construct one perpendicular to them both, which is to take a cross product of the two you have
answered Dec 28 '18 at 16:27
gt6989b
33k22452
33k22452
Thank you for the help!:)
– Miguel Ferreira
Dec 28 '18 at 17:10
add a comment |
Thank you for the help!:)
– Miguel Ferreira
Dec 28 '18 at 17:10
Thank you for the help!:)
– Miguel Ferreira
Dec 28 '18 at 17:10
Thank you for the help!:)
– Miguel Ferreira
Dec 28 '18 at 17:10
add a comment |
Just take the cross product:
$$(2,3,1) times (1,4,3) = (5,-5,5)$$
Then ${(2,3,1),(1,4,3),(5,-5,5)}$ is linearly independent and hence a basis for $mathbb{R}^3$.
Thank you for the help! Didn't know about this method :)
– Miguel Ferreira
Dec 28 '18 at 17:17
add a comment |
Just take the cross product:
$$(2,3,1) times (1,4,3) = (5,-5,5)$$
Then ${(2,3,1),(1,4,3),(5,-5,5)}$ is linearly independent and hence a basis for $mathbb{R}^3$.
Thank you for the help! Didn't know about this method :)
– Miguel Ferreira
Dec 28 '18 at 17:17
add a comment |
Just take the cross product:
$$(2,3,1) times (1,4,3) = (5,-5,5)$$
Then ${(2,3,1),(1,4,3),(5,-5,5)}$ is linearly independent and hence a basis for $mathbb{R}^3$.
Just take the cross product:
$$(2,3,1) times (1,4,3) = (5,-5,5)$$
Then ${(2,3,1),(1,4,3),(5,-5,5)}$ is linearly independent and hence a basis for $mathbb{R}^3$.
answered Dec 28 '18 at 16:52
mechanodroid
26.2k62245
26.2k62245
Thank you for the help! Didn't know about this method :)
– Miguel Ferreira
Dec 28 '18 at 17:17
add a comment |
Thank you for the help! Didn't know about this method :)
– Miguel Ferreira
Dec 28 '18 at 17:17
Thank you for the help! Didn't know about this method :)
– Miguel Ferreira
Dec 28 '18 at 17:17
Thank you for the help! Didn't know about this method :)
– Miguel Ferreira
Dec 28 '18 at 17:17
add a comment |
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