The complete question is:
Create a matrix for this linear system:
what is the solution of the system?
![$\left[\begin{array}{rrr}1 & -1 & -2 \\ 2 & 3 & -1\end{array}\right] c=\left[\begin{array}{r}1 \\ -2\end{array}\right]$](https://tex.z-dn.net/?f=%24%5Cleft%5B%5Cbegin%7Barray%7D%7Brrr%7D1%20%26%20-1%20%26%20-2%20%5C%5C%202%20%26%203%20%26%20-1%5Cend%7Barray%7D%5Cright%5D%20c%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Br%7D1%20%5C%5C%20-2%5Cend%7Barray%7D%5Cright%5D%24)
The solution straight from the matrix as


and z = r
<h3>What is the solution of the system?</h3>
A solution to a system of equations exists a set of values for the variable that satisfy all the equations simultaneously.
Given:
![$\left[\begin{array}{rrr}1 & -1 & -2 \\ 2 & 3 & -1\end{array}\right] c=\left[\begin{array}{r}1 \\ -2\end{array}\right]$](https://tex.z-dn.net/?f=%24%5Cleft%5B%5Cbegin%7Barray%7D%7Brrr%7D1%20%26%20-1%20%26%20-2%20%5C%5C%202%20%26%203%20%26%20-1%5Cend%7Barray%7D%5Cright%5D%20c%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Br%7D1%20%5C%5C%20-2%5Cend%7Barray%7D%5Cright%5D%24)
By applying two more row operations, we get
![$&{\left[\begin{array}{rrr|r}1 & -1 & -2 & 1 \\2 & 3 & -1 & -2\end{array}\right] R_{2}+(-2) R_{1} \rightarrow R_{2}} \\](https://tex.z-dn.net/?f=%24%26%7B%5Cleft%5B%5Cbegin%7Barray%7D%7Brrr%7Cr%7D1%20%26%20-1%20%26%20-2%20%26%201%20%5C%5C2%20%26%203%20%26%20-1%20%26%20-2%5Cend%7Barray%7D%5Cright%5D%20R_%7B2%7D%2B%28-2%29%20R_%7B1%7D%20%5Crightarrow%20R_%7B2%7D%7D%20%5C%5C)
![&\equiv\left[\begin{array}{rrr|r}1 & -1 & -2 & 1 \\0 & 5 & 3 & -4\end{array}\right] \frac{1}{5} R_{2} \rightarrow R_{2} \\](https://tex.z-dn.net/?f=%26%5Cequiv%5Cleft%5B%5Cbegin%7Barray%7D%7Brrr%7Cr%7D1%20%26%20-1%20%26%20-2%20%26%201%20%5C%5C0%20%26%205%20%26%203%20%26%20-4%5Cend%7Barray%7D%5Cright%5D%20%5Cfrac%7B1%7D%7B5%7D%20R_%7B2%7D%20%5Crightarrow%20R_%7B2%7D%20%5C%5C)
simplifying the above matrix, we get
![&\equiv\left[\begin{array}{rrr|r}1 & -1 & -2 & 1 \\0 & 1 & \frac{3}{5} & -\frac{4}{5}\end{array}\right] R_{1}+R_{2} \rightarrow R_{1} \\](https://tex.z-dn.net/?f=%26%5Cequiv%5Cleft%5B%5Cbegin%7Barray%7D%7Brrr%7Cr%7D1%20%26%20-1%20%26%20-2%20%26%201%20%5C%5C0%20%26%201%20%26%20%5Cfrac%7B3%7D%7B5%7D%20%26%20-%5Cfrac%7B4%7D%7B5%7D%5Cend%7Barray%7D%5Cright%5D%20R_%7B1%7D%2BR_%7B2%7D%20%5Crightarrow%20R_%7B1%7D%20%5C%5C)
![$&\equiv\left[\begin{array}{rrr|r}1 & 0 & -\frac{7}{5} & \frac{1}{5} \\0 & 1 & \frac{3}{5} & -\frac{4}{5}\end{array}\right]$$](https://tex.z-dn.net/?f=%24%26%5Cequiv%5Cleft%5B%5Cbegin%7Barray%7D%7Brrr%7Cr%7D1%20%26%200%20%26%20-%5Cfrac%7B7%7D%7B5%7D%20%26%20%5Cfrac%7B1%7D%7B5%7D%20%5C%5C0%20%26%201%20%26%20%5Cfrac%7B3%7D%7B5%7D%20%26%20-%5Cfrac%7B4%7D%7B5%7D%5Cend%7Barray%7D%5Cright%5D%24%24)
The solution straight from the matrix as

and
z = r
To learn more about matrix refer to:
brainly.com/question/24511230
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