How could this this equation system be transformed to a X-Y-Z linear equation system?












1












$begingroup$


I'm trying to solve this problem, which basically states this:




Based on the system of equations of the variables $x, y$ and $z$:
$$begin{cases}
x y - 2sqrt{y} + 3 y z = 8 \
2 x y - 3sqrt{y} + 2 y z = 7 \
- x y + sqrt{y} + 2 y z = 4 \
end{cases}$$
please tell which of the next alternatives are correct:




  • The system is possible and determined

  • The range of the extended matrix of the system is 2.

  • On the transposed matrix of the coefficients, associated with the system: $a_{12} = -3$

  • The coefficient matrix associated to the system is non invertible.




So, what I did was construct the extended matrix from the equation system given in the problem statement, replacing the variables as this:




  • $a = xy$

  • $b = sqrt{y}$

  • $c = yz$


The matrix constructed is this:
begin{bmatrix}
1 & -2 & 3 & 8 \
2 & -3 & 2 & 7 \
-1 & 1 & 2 & 4
end{bmatrix}

Solving by gaussian method, the matrix is reduced to:
begin{bmatrix}
1 & -2 & 3 & 8 \
0 & 1 & -4 & -9 \
0 & 0 & 1 & 3
end{bmatrix}



So finally:




  • $a = 5$

  • $b = 3$

  • $c = 3$


The values of $x, y$ and $z$ could be calculated using the previous equations, giving this values as results:




  • $x = 5/9$

  • $y = 9$

  • $z = 1/3$


This is the far as I can go on solving this problem, my question basically is, how to transform this to a linear equation system of x, y and z, because I do have the values of $x, y$ and $z$ but the statements that I have to indicate if they are correct or not, are based on that matrix that I don't know how to build.



I was thinking that maybe this problem doesn't look for me to build such a matrix, instead, given that there exist a solution for the system proposed initially, I should deduct the veracity of the statements:




  • First statement is correct as each variable has just one unique value.

  • Second statement is incorrect because for each variable having one single value, the range of the matrix should be 3.


Second and third statement I have no idea how to answer to.



Please give me a hand on this.
Thank you a lot.










share|cite|improve this question











$endgroup$












  • $begingroup$
    It is important to include the entire question as text, instead of as images. I added the necessary MathJax for you.
    $endgroup$
    – Nominal Animal
    Jan 13 at 0:56










  • $begingroup$
    Thank you for including it!
    $endgroup$
    – Carlos Córdova S.
    Jan 13 at 0:58






  • 1




    $begingroup$
    I suspect that the matrix-related items refer to the coefficients of the linear "$a$-$b$-$c$" system you created by assigning $a=xy$, $b=sqrt{y}$, $c=yz$.
    $endgroup$
    – Blue
    Jan 13 at 1:13










  • $begingroup$
    It is not, the problem said "Based on the equation system of the variables "x-y-z"
    $endgroup$
    – Carlos Córdova S.
    Jan 13 at 1:15






  • 3




    $begingroup$
    @CarlosCórdovaS.: Well, the $x$-$y$-$z$ system is hopelessly non-linear, so there's no appropriate interpretation of "matrix of coefficients" for it. (The work you did in assigning $a$, $b$, $c$ seems exactly the correct approach.)
    $endgroup$
    – Blue
    Jan 13 at 1:20


















1












$begingroup$


I'm trying to solve this problem, which basically states this:




Based on the system of equations of the variables $x, y$ and $z$:
$$begin{cases}
x y - 2sqrt{y} + 3 y z = 8 \
2 x y - 3sqrt{y} + 2 y z = 7 \
- x y + sqrt{y} + 2 y z = 4 \
end{cases}$$
please tell which of the next alternatives are correct:




  • The system is possible and determined

  • The range of the extended matrix of the system is 2.

  • On the transposed matrix of the coefficients, associated with the system: $a_{12} = -3$

  • The coefficient matrix associated to the system is non invertible.




So, what I did was construct the extended matrix from the equation system given in the problem statement, replacing the variables as this:




  • $a = xy$

  • $b = sqrt{y}$

  • $c = yz$


The matrix constructed is this:
begin{bmatrix}
1 & -2 & 3 & 8 \
2 & -3 & 2 & 7 \
-1 & 1 & 2 & 4
end{bmatrix}

Solving by gaussian method, the matrix is reduced to:
begin{bmatrix}
1 & -2 & 3 & 8 \
0 & 1 & -4 & -9 \
0 & 0 & 1 & 3
end{bmatrix}



So finally:




  • $a = 5$

  • $b = 3$

  • $c = 3$


The values of $x, y$ and $z$ could be calculated using the previous equations, giving this values as results:




  • $x = 5/9$

  • $y = 9$

  • $z = 1/3$


This is the far as I can go on solving this problem, my question basically is, how to transform this to a linear equation system of x, y and z, because I do have the values of $x, y$ and $z$ but the statements that I have to indicate if they are correct or not, are based on that matrix that I don't know how to build.



I was thinking that maybe this problem doesn't look for me to build such a matrix, instead, given that there exist a solution for the system proposed initially, I should deduct the veracity of the statements:




  • First statement is correct as each variable has just one unique value.

  • Second statement is incorrect because for each variable having one single value, the range of the matrix should be 3.


Second and third statement I have no idea how to answer to.



Please give me a hand on this.
Thank you a lot.










share|cite|improve this question











$endgroup$












  • $begingroup$
    It is important to include the entire question as text, instead of as images. I added the necessary MathJax for you.
    $endgroup$
    – Nominal Animal
    Jan 13 at 0:56










  • $begingroup$
    Thank you for including it!
    $endgroup$
    – Carlos Córdova S.
    Jan 13 at 0:58






  • 1




    $begingroup$
    I suspect that the matrix-related items refer to the coefficients of the linear "$a$-$b$-$c$" system you created by assigning $a=xy$, $b=sqrt{y}$, $c=yz$.
    $endgroup$
    – Blue
    Jan 13 at 1:13










  • $begingroup$
    It is not, the problem said "Based on the equation system of the variables "x-y-z"
    $endgroup$
    – Carlos Córdova S.
    Jan 13 at 1:15






  • 3




    $begingroup$
    @CarlosCórdovaS.: Well, the $x$-$y$-$z$ system is hopelessly non-linear, so there's no appropriate interpretation of "matrix of coefficients" for it. (The work you did in assigning $a$, $b$, $c$ seems exactly the correct approach.)
    $endgroup$
    – Blue
    Jan 13 at 1:20
















1












1








1





$begingroup$


I'm trying to solve this problem, which basically states this:




Based on the system of equations of the variables $x, y$ and $z$:
$$begin{cases}
x y - 2sqrt{y} + 3 y z = 8 \
2 x y - 3sqrt{y} + 2 y z = 7 \
- x y + sqrt{y} + 2 y z = 4 \
end{cases}$$
please tell which of the next alternatives are correct:




  • The system is possible and determined

  • The range of the extended matrix of the system is 2.

  • On the transposed matrix of the coefficients, associated with the system: $a_{12} = -3$

  • The coefficient matrix associated to the system is non invertible.




So, what I did was construct the extended matrix from the equation system given in the problem statement, replacing the variables as this:




  • $a = xy$

  • $b = sqrt{y}$

  • $c = yz$


The matrix constructed is this:
begin{bmatrix}
1 & -2 & 3 & 8 \
2 & -3 & 2 & 7 \
-1 & 1 & 2 & 4
end{bmatrix}

Solving by gaussian method, the matrix is reduced to:
begin{bmatrix}
1 & -2 & 3 & 8 \
0 & 1 & -4 & -9 \
0 & 0 & 1 & 3
end{bmatrix}



So finally:




  • $a = 5$

  • $b = 3$

  • $c = 3$


The values of $x, y$ and $z$ could be calculated using the previous equations, giving this values as results:




  • $x = 5/9$

  • $y = 9$

  • $z = 1/3$


This is the far as I can go on solving this problem, my question basically is, how to transform this to a linear equation system of x, y and z, because I do have the values of $x, y$ and $z$ but the statements that I have to indicate if they are correct or not, are based on that matrix that I don't know how to build.



I was thinking that maybe this problem doesn't look for me to build such a matrix, instead, given that there exist a solution for the system proposed initially, I should deduct the veracity of the statements:




  • First statement is correct as each variable has just one unique value.

  • Second statement is incorrect because for each variable having one single value, the range of the matrix should be 3.


Second and third statement I have no idea how to answer to.



Please give me a hand on this.
Thank you a lot.










share|cite|improve this question











$endgroup$




I'm trying to solve this problem, which basically states this:




Based on the system of equations of the variables $x, y$ and $z$:
$$begin{cases}
x y - 2sqrt{y} + 3 y z = 8 \
2 x y - 3sqrt{y} + 2 y z = 7 \
- x y + sqrt{y} + 2 y z = 4 \
end{cases}$$
please tell which of the next alternatives are correct:




  • The system is possible and determined

  • The range of the extended matrix of the system is 2.

  • On the transposed matrix of the coefficients, associated with the system: $a_{12} = -3$

  • The coefficient matrix associated to the system is non invertible.




So, what I did was construct the extended matrix from the equation system given in the problem statement, replacing the variables as this:




  • $a = xy$

  • $b = sqrt{y}$

  • $c = yz$


The matrix constructed is this:
begin{bmatrix}
1 & -2 & 3 & 8 \
2 & -3 & 2 & 7 \
-1 & 1 & 2 & 4
end{bmatrix}

Solving by gaussian method, the matrix is reduced to:
begin{bmatrix}
1 & -2 & 3 & 8 \
0 & 1 & -4 & -9 \
0 & 0 & 1 & 3
end{bmatrix}



So finally:




  • $a = 5$

  • $b = 3$

  • $c = 3$


The values of $x, y$ and $z$ could be calculated using the previous equations, giving this values as results:




  • $x = 5/9$

  • $y = 9$

  • $z = 1/3$


This is the far as I can go on solving this problem, my question basically is, how to transform this to a linear equation system of x, y and z, because I do have the values of $x, y$ and $z$ but the statements that I have to indicate if they are correct or not, are based on that matrix that I don't know how to build.



I was thinking that maybe this problem doesn't look for me to build such a matrix, instead, given that there exist a solution for the system proposed initially, I should deduct the veracity of the statements:




  • First statement is correct as each variable has just one unique value.

  • Second statement is incorrect because for each variable having one single value, the range of the matrix should be 3.


Second and third statement I have no idea how to answer to.



Please give me a hand on this.
Thank you a lot.







linear-algebra systems-of-equations






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 13 at 1:15







Carlos Córdova S.

















asked Jan 13 at 0:49









Carlos Córdova S.Carlos Córdova S.

134




134












  • $begingroup$
    It is important to include the entire question as text, instead of as images. I added the necessary MathJax for you.
    $endgroup$
    – Nominal Animal
    Jan 13 at 0:56










  • $begingroup$
    Thank you for including it!
    $endgroup$
    – Carlos Córdova S.
    Jan 13 at 0:58






  • 1




    $begingroup$
    I suspect that the matrix-related items refer to the coefficients of the linear "$a$-$b$-$c$" system you created by assigning $a=xy$, $b=sqrt{y}$, $c=yz$.
    $endgroup$
    – Blue
    Jan 13 at 1:13










  • $begingroup$
    It is not, the problem said "Based on the equation system of the variables "x-y-z"
    $endgroup$
    – Carlos Córdova S.
    Jan 13 at 1:15






  • 3




    $begingroup$
    @CarlosCórdovaS.: Well, the $x$-$y$-$z$ system is hopelessly non-linear, so there's no appropriate interpretation of "matrix of coefficients" for it. (The work you did in assigning $a$, $b$, $c$ seems exactly the correct approach.)
    $endgroup$
    – Blue
    Jan 13 at 1:20




















  • $begingroup$
    It is important to include the entire question as text, instead of as images. I added the necessary MathJax for you.
    $endgroup$
    – Nominal Animal
    Jan 13 at 0:56










  • $begingroup$
    Thank you for including it!
    $endgroup$
    – Carlos Córdova S.
    Jan 13 at 0:58






  • 1




    $begingroup$
    I suspect that the matrix-related items refer to the coefficients of the linear "$a$-$b$-$c$" system you created by assigning $a=xy$, $b=sqrt{y}$, $c=yz$.
    $endgroup$
    – Blue
    Jan 13 at 1:13










  • $begingroup$
    It is not, the problem said "Based on the equation system of the variables "x-y-z"
    $endgroup$
    – Carlos Córdova S.
    Jan 13 at 1:15






  • 3




    $begingroup$
    @CarlosCórdovaS.: Well, the $x$-$y$-$z$ system is hopelessly non-linear, so there's no appropriate interpretation of "matrix of coefficients" for it. (The work you did in assigning $a$, $b$, $c$ seems exactly the correct approach.)
    $endgroup$
    – Blue
    Jan 13 at 1:20


















$begingroup$
It is important to include the entire question as text, instead of as images. I added the necessary MathJax for you.
$endgroup$
– Nominal Animal
Jan 13 at 0:56




$begingroup$
It is important to include the entire question as text, instead of as images. I added the necessary MathJax for you.
$endgroup$
– Nominal Animal
Jan 13 at 0:56












$begingroup$
Thank you for including it!
$endgroup$
– Carlos Córdova S.
Jan 13 at 0:58




$begingroup$
Thank you for including it!
$endgroup$
– Carlos Córdova S.
Jan 13 at 0:58




1




1




$begingroup$
I suspect that the matrix-related items refer to the coefficients of the linear "$a$-$b$-$c$" system you created by assigning $a=xy$, $b=sqrt{y}$, $c=yz$.
$endgroup$
– Blue
Jan 13 at 1:13




$begingroup$
I suspect that the matrix-related items refer to the coefficients of the linear "$a$-$b$-$c$" system you created by assigning $a=xy$, $b=sqrt{y}$, $c=yz$.
$endgroup$
– Blue
Jan 13 at 1:13












$begingroup$
It is not, the problem said "Based on the equation system of the variables "x-y-z"
$endgroup$
– Carlos Córdova S.
Jan 13 at 1:15




$begingroup$
It is not, the problem said "Based on the equation system of the variables "x-y-z"
$endgroup$
– Carlos Córdova S.
Jan 13 at 1:15




3




3




$begingroup$
@CarlosCórdovaS.: Well, the $x$-$y$-$z$ system is hopelessly non-linear, so there's no appropriate interpretation of "matrix of coefficients" for it. (The work you did in assigning $a$, $b$, $c$ seems exactly the correct approach.)
$endgroup$
– Blue
Jan 13 at 1:20






$begingroup$
@CarlosCórdovaS.: Well, the $x$-$y$-$z$ system is hopelessly non-linear, so there's no appropriate interpretation of "matrix of coefficients" for it. (The work you did in assigning $a$, $b$, $c$ seems exactly the correct approach.)
$endgroup$
– Blue
Jan 13 at 1:20












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