Complete ${(2,3,1),(1,4,3)}$ to a basis of $Bbb R^3$
$begingroup$
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 $3$, $C$ needs $3$ elements. 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
$endgroup$
add a comment |
$begingroup$
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 $3$, $C$ needs $3$ elements. 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
$endgroup$
add a comment |
$begingroup$
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 $3$, $C$ needs $3$ elements. 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
$endgroup$
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 $3$, $C$ needs $3$ elements. 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 Feb 20 at 16:34
José Carlos Santos
175k24134243
175k24134243
asked Dec 28 '18 at 16:23
Miguel FerreiraMiguel Ferreira
885
885
add a comment |
add a comment |
4 Answers
4
active
oldest
votes
$begingroup$
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. Actually, any vector $(a,b,c)$ such that $bneq a+c$ will do.
$endgroup$
add a comment |
$begingroup$
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.
$endgroup$
$begingroup$
Thank you very much for the help!
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:16
add a comment |
$begingroup$
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
$endgroup$
$begingroup$
Thank you for the help!:)
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:10
add a comment |
$begingroup$
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 $mathbb{R}^3$.
$endgroup$
$begingroup$
Thank you for the help! Didn't know about this method :)
$endgroup$
– 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
$begingroup$
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. Actually, any vector $(a,b,c)$ such that $bneq a+c$ will do.
$endgroup$
add a comment |
$begingroup$
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. Actually, any vector $(a,b,c)$ such that $bneq a+c$ will do.
$endgroup$
add a comment |
$begingroup$
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. Actually, any vector $(a,b,c)$ such that $bneq a+c$ will do.
$endgroup$
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. Actually, any vector $(a,b,c)$ such that $bneq a+c$ will do.
edited Mar 1 at 19:47
answered Dec 28 '18 at 16:27
José Carlos SantosJosé Carlos Santos
175k24134243
175k24134243
add a comment |
add a comment |
$begingroup$
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.
$endgroup$
$begingroup$
Thank you very much for the help!
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:16
add a comment |
$begingroup$
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.
$endgroup$
$begingroup$
Thank you very much for the help!
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:16
add a comment |
$begingroup$
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.
$endgroup$
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
YankoYanko
8,4692830
8,4692830
$begingroup$
Thank you very much for the help!
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:16
add a comment |
$begingroup$
Thank you very much for the help!
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:16
$begingroup$
Thank you very much for the help!
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:16
$begingroup$
Thank you very much for the help!
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:16
add a comment |
$begingroup$
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
$endgroup$
$begingroup$
Thank you for the help!:)
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:10
add a comment |
$begingroup$
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
$endgroup$
$begingroup$
Thank you for the help!:)
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:10
add a comment |
$begingroup$
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
$endgroup$
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
gt6989bgt6989b
36k22557
36k22557
$begingroup$
Thank you for the help!:)
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:10
add a comment |
$begingroup$
Thank you for the help!:)
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:10
$begingroup$
Thank you for the help!:)
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:10
$begingroup$
Thank you for the help!:)
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:10
add a comment |
$begingroup$
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 $mathbb{R}^3$.
$endgroup$
$begingroup$
Thank you for the help! Didn't know about this method :)
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:17
add a comment |
$begingroup$
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 $mathbb{R}^3$.
$endgroup$
$begingroup$
Thank you for the help! Didn't know about this method :)
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:17
add a comment |
$begingroup$
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 $mathbb{R}^3$.
$endgroup$
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
mechanodroidmechanodroid
28.9k62648
28.9k62648
$begingroup$
Thank you for the help! Didn't know about this method :)
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:17
add a comment |
$begingroup$
Thank you for the help! Didn't know about this method :)
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:17
$begingroup$
Thank you for the help! Didn't know about this method :)
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:17
$begingroup$
Thank you for the help! Didn't know about this method :)
$endgroup$
– Miguel Ferreira
Dec 28 '18 at 17:17
add a comment |
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