Determine which of the following are Vector Spaces












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enter image description here



Going off the axioms, I'm trying to determine how to verify each of these. In the first set, do I take $u = (x_1, x_2, x_3)$ and $v = (y_1, y_2, y_3)$, or would it rather be $u = (x_1 + y_1, x_2 + y_2, x_3 + y_3), v = (x_4 + y_4, x_5 + y_5, x_6 + y_6)$?



Based on what I know about scalar multiplication, I would say the first set is not a vector space because $0(x_1, x_2, x_3)$ = $(0, 0, 0)$ which is not equivalent to $(0x_1, x_2, x_3)$, for non-zero values of $x_2$ and $x_3$. The second and third sets seem to define vector spaces, as I can't seem to figure out any axiom that directly fails (i.e. $u+v$ is in $V$, a unique additive identity exists, and the set is closed under scalar multiplication). Any help would be appreciated.



Edit: The third set is not a vector space.










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$endgroup$

















    1












    $begingroup$


    enter image description here



    Going off the axioms, I'm trying to determine how to verify each of these. In the first set, do I take $u = (x_1, x_2, x_3)$ and $v = (y_1, y_2, y_3)$, or would it rather be $u = (x_1 + y_1, x_2 + y_2, x_3 + y_3), v = (x_4 + y_4, x_5 + y_5, x_6 + y_6)$?



    Based on what I know about scalar multiplication, I would say the first set is not a vector space because $0(x_1, x_2, x_3)$ = $(0, 0, 0)$ which is not equivalent to $(0x_1, x_2, x_3)$, for non-zero values of $x_2$ and $x_3$. The second and third sets seem to define vector spaces, as I can't seem to figure out any axiom that directly fails (i.e. $u+v$ is in $V$, a unique additive identity exists, and the set is closed under scalar multiplication). Any help would be appreciated.



    Edit: The third set is not a vector space.










    share|cite|improve this question











    $endgroup$















      1












      1








      1





      $begingroup$


      enter image description here



      Going off the axioms, I'm trying to determine how to verify each of these. In the first set, do I take $u = (x_1, x_2, x_3)$ and $v = (y_1, y_2, y_3)$, or would it rather be $u = (x_1 + y_1, x_2 + y_2, x_3 + y_3), v = (x_4 + y_4, x_5 + y_5, x_6 + y_6)$?



      Based on what I know about scalar multiplication, I would say the first set is not a vector space because $0(x_1, x_2, x_3)$ = $(0, 0, 0)$ which is not equivalent to $(0x_1, x_2, x_3)$, for non-zero values of $x_2$ and $x_3$. The second and third sets seem to define vector spaces, as I can't seem to figure out any axiom that directly fails (i.e. $u+v$ is in $V$, a unique additive identity exists, and the set is closed under scalar multiplication). Any help would be appreciated.



      Edit: The third set is not a vector space.










      share|cite|improve this question











      $endgroup$




      enter image description here



      Going off the axioms, I'm trying to determine how to verify each of these. In the first set, do I take $u = (x_1, x_2, x_3)$ and $v = (y_1, y_2, y_3)$, or would it rather be $u = (x_1 + y_1, x_2 + y_2, x_3 + y_3), v = (x_4 + y_4, x_5 + y_5, x_6 + y_6)$?



      Based on what I know about scalar multiplication, I would say the first set is not a vector space because $0(x_1, x_2, x_3)$ = $(0, 0, 0)$ which is not equivalent to $(0x_1, x_2, x_3)$, for non-zero values of $x_2$ and $x_3$. The second and third sets seem to define vector spaces, as I can't seem to figure out any axiom that directly fails (i.e. $u+v$ is in $V$, a unique additive identity exists, and the set is closed under scalar multiplication). Any help would be appreciated.



      Edit: The third set is not a vector space.







      linear-algebra vector-spaces vectors






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      share|cite|improve this question













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      edited Jan 22 at 5:46







      Sanjoy The Manjoy

















      asked Jan 22 at 4:58









      Sanjoy The ManjoySanjoy The Manjoy

      493315




      493315






















          1 Answer
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          $begingroup$

          The third one is not a vector space. The zero vector in this space is $(-1,-1)$ but if you multiply this by $2$ you don't get back the zero vector.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Ahh thank you! My Linear Algebra is very rusty right now, so these problems are helping me refresh. For the first set, what would you set the $u$ and $v$ vectors as when checking for $u+v$
            $endgroup$
            – Sanjoy The Manjoy
            Jan 22 at 5:46






          • 1




            $begingroup$
            @SanjoyTheManjoy In the first example all properties of addition are satisfied. It is teh scalar multiplication (and its relation to addition) that is a problem.
            $endgroup$
            – Kavi Rama Murthy
            Jan 22 at 5:51










          • $begingroup$
            Right, I figured as much, but to verify that axiom of addition holds, do I let u = $(x_1, x_2, x_3)$ or rather u = $(x_1 + y_1,...)$
            $endgroup$
            – Sanjoy The Manjoy
            Jan 22 at 5:52











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          1 Answer
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          $begingroup$

          The third one is not a vector space. The zero vector in this space is $(-1,-1)$ but if you multiply this by $2$ you don't get back the zero vector.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Ahh thank you! My Linear Algebra is very rusty right now, so these problems are helping me refresh. For the first set, what would you set the $u$ and $v$ vectors as when checking for $u+v$
            $endgroup$
            – Sanjoy The Manjoy
            Jan 22 at 5:46






          • 1




            $begingroup$
            @SanjoyTheManjoy In the first example all properties of addition are satisfied. It is teh scalar multiplication (and its relation to addition) that is a problem.
            $endgroup$
            – Kavi Rama Murthy
            Jan 22 at 5:51










          • $begingroup$
            Right, I figured as much, but to verify that axiom of addition holds, do I let u = $(x_1, x_2, x_3)$ or rather u = $(x_1 + y_1,...)$
            $endgroup$
            – Sanjoy The Manjoy
            Jan 22 at 5:52
















          2












          $begingroup$

          The third one is not a vector space. The zero vector in this space is $(-1,-1)$ but if you multiply this by $2$ you don't get back the zero vector.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Ahh thank you! My Linear Algebra is very rusty right now, so these problems are helping me refresh. For the first set, what would you set the $u$ and $v$ vectors as when checking for $u+v$
            $endgroup$
            – Sanjoy The Manjoy
            Jan 22 at 5:46






          • 1




            $begingroup$
            @SanjoyTheManjoy In the first example all properties of addition are satisfied. It is teh scalar multiplication (and its relation to addition) that is a problem.
            $endgroup$
            – Kavi Rama Murthy
            Jan 22 at 5:51










          • $begingroup$
            Right, I figured as much, but to verify that axiom of addition holds, do I let u = $(x_1, x_2, x_3)$ or rather u = $(x_1 + y_1,...)$
            $endgroup$
            – Sanjoy The Manjoy
            Jan 22 at 5:52














          2












          2








          2





          $begingroup$

          The third one is not a vector space. The zero vector in this space is $(-1,-1)$ but if you multiply this by $2$ you don't get back the zero vector.






          share|cite|improve this answer









          $endgroup$



          The third one is not a vector space. The zero vector in this space is $(-1,-1)$ but if you multiply this by $2$ you don't get back the zero vector.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Jan 22 at 5:34









          Kavi Rama MurthyKavi Rama Murthy

          65.7k42767




          65.7k42767












          • $begingroup$
            Ahh thank you! My Linear Algebra is very rusty right now, so these problems are helping me refresh. For the first set, what would you set the $u$ and $v$ vectors as when checking for $u+v$
            $endgroup$
            – Sanjoy The Manjoy
            Jan 22 at 5:46






          • 1




            $begingroup$
            @SanjoyTheManjoy In the first example all properties of addition are satisfied. It is teh scalar multiplication (and its relation to addition) that is a problem.
            $endgroup$
            – Kavi Rama Murthy
            Jan 22 at 5:51










          • $begingroup$
            Right, I figured as much, but to verify that axiom of addition holds, do I let u = $(x_1, x_2, x_3)$ or rather u = $(x_1 + y_1,...)$
            $endgroup$
            – Sanjoy The Manjoy
            Jan 22 at 5:52


















          • $begingroup$
            Ahh thank you! My Linear Algebra is very rusty right now, so these problems are helping me refresh. For the first set, what would you set the $u$ and $v$ vectors as when checking for $u+v$
            $endgroup$
            – Sanjoy The Manjoy
            Jan 22 at 5:46






          • 1




            $begingroup$
            @SanjoyTheManjoy In the first example all properties of addition are satisfied. It is teh scalar multiplication (and its relation to addition) that is a problem.
            $endgroup$
            – Kavi Rama Murthy
            Jan 22 at 5:51










          • $begingroup$
            Right, I figured as much, but to verify that axiom of addition holds, do I let u = $(x_1, x_2, x_3)$ or rather u = $(x_1 + y_1,...)$
            $endgroup$
            – Sanjoy The Manjoy
            Jan 22 at 5:52
















          $begingroup$
          Ahh thank you! My Linear Algebra is very rusty right now, so these problems are helping me refresh. For the first set, what would you set the $u$ and $v$ vectors as when checking for $u+v$
          $endgroup$
          – Sanjoy The Manjoy
          Jan 22 at 5:46




          $begingroup$
          Ahh thank you! My Linear Algebra is very rusty right now, so these problems are helping me refresh. For the first set, what would you set the $u$ and $v$ vectors as when checking for $u+v$
          $endgroup$
          – Sanjoy The Manjoy
          Jan 22 at 5:46




          1




          1




          $begingroup$
          @SanjoyTheManjoy In the first example all properties of addition are satisfied. It is teh scalar multiplication (and its relation to addition) that is a problem.
          $endgroup$
          – Kavi Rama Murthy
          Jan 22 at 5:51




          $begingroup$
          @SanjoyTheManjoy In the first example all properties of addition are satisfied. It is teh scalar multiplication (and its relation to addition) that is a problem.
          $endgroup$
          – Kavi Rama Murthy
          Jan 22 at 5:51












          $begingroup$
          Right, I figured as much, but to verify that axiom of addition holds, do I let u = $(x_1, x_2, x_3)$ or rather u = $(x_1 + y_1,...)$
          $endgroup$
          – Sanjoy The Manjoy
          Jan 22 at 5:52




          $begingroup$
          Right, I figured as much, but to verify that axiom of addition holds, do I let u = $(x_1, x_2, x_3)$ or rather u = $(x_1 + y_1,...)$
          $endgroup$
          – Sanjoy The Manjoy
          Jan 22 at 5:52


















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