Question

Solve the 3 × 3 system shown below. Enter the values of x, y, and z. X + 2y – z = –3 (1) 2x – y + z = 5 (2) x – y + z = 4 (3)

Answer 1

Answer:

$\boxed{x=1, \y=-1, \ z=2}$

Step-by-step explanation:

We will use the Gaussian elimination method to solve this problem. To do so, let's follow the following steps:

Step 1: Let's multiply first equation by −2. Next, add the result to the second equation. So:

$\begin{array}{ cccc }~~ x&+~~2~ y&-~~~~~ z&~=~-3\\&-~~~5~ y&+~~3~ z&~=~11\\~~ x&-~~~~~ y&+~~~~ z&~=~4\end{array}$

Step 2: Let's multiply first equation by −1. Next, add the result to the third equation. Thus:

$\begin{array}{ cccc }~~ x&+~~2~ y&-~~~~~ z&~=~-3\\&-~~~5~ y&+~~3~ z&~=~11\\&-~~~3~ y&+~~2~ z&~=~7\end{array}$

Step 3: Let's multiply second equation by −35, Next, add the result to the third equation. Therefore:

$\begin{array}{ cccc }~~ x&+~~2~ y&-~~~~~ z&~=~-3\\&-~~~5~ y&+~~3~ z&~=~11\\&&+~~\frac{ 1 }{ 5 }~ z&~=~\frac{ 2 }{ 5 }\end{array}$

Step 4: solve for z, then for y, then for x:

$\frac{ 1 }{ 5 } ~ z & = \frac{ 2 }{ 5 } \\ \\ \boxed{z & = 2}$

$-5y+3z &= 11\\-5y+3\cdot 2 &= 11\\ \\ \boxed{y &= -1}$

By substituting $y=-1 \ and \ z=2$ into the first equation, we get the $x$. So:

$x+2(-1)-2=-3 \\ \\ x-2-2=-3 \\ \\ \boxed{x=1}$

Answer 2

Answer:

X= 1, y= -1, z= 2

Step-by-step explanation: