What is the solution to the following system?

[tex]\[
\begin{cases}
4x + 3y - z = -6 \\
6x - y + 3z = 12 \\
8x + 2y + 4z = 6
\end{cases}
\][/tex]

A. [tex]\( x = 1, y = -3, z = -1 \)[/tex]
B. [tex]\( x = 1, y = -3, z = 1 \)[/tex]
C. [tex]\( x = 1, y = 3, z = 19 \)[/tex]
D. [tex]\( x = 1, y = 3, z = -2 \)[/tex]



Answer :

To find the solution to the system of linear equations given by:

[tex]\[ \left\{\begin{array}{l} 4x + 3y - z = -6 \\ 6x - y + 3z = 12 \\ 8x + 2y + 4z = 6 \end{array}\right. \][/tex]

let's verify the solutions step-by-step for consistency. Here are the steps to determine the correct values of [tex]\(x\)[/tex], [tex]\(y\)[/tex], and [tex]\(z\)[/tex]:

### Step 1: Verify the Equation 1

Substituting the given values into the first equation:
[tex]\[ 4x + 3y - z = -6 \][/tex]

Let's test the solutions:

Option 1: [tex]\( x = 1, y = -3, z = -1 \)[/tex]

[tex]\[ 4(1) + 3(-3) - (-1) = 4 - 9 + 1 = -4 \quad (\text{Not equal to } -6) \][/tex]

Option 2: [tex]\( x = 1, y = -3, z = 1 \)[/tex]

[tex]\[ 4(1) + 3(-3) - 1 = 4 - 9 - 1 = -6 \quad (\text{Correct}) \][/tex]

Option 3: [tex]\( x = 1, y = 3, z = 19 \)[/tex]

[tex]\[ 4(1) + 3(3) - 19 = 4 + 9 - 19 = -6 \quad (\text{Correct}) \][/tex]

Option 4: [tex]\( x = 1, y = 3, z = -2 \)[/tex]

[tex]\[ 4(1) + 3(3) + 2 = 4 + 9 + 2 = 15 \quad (\text{Not equal to } -6) \][/tex]

### Step 2: Verify the Equation 2

Substituting the given values into the second equation:
[tex]\[ 6x - y + 3z = 12 \][/tex]

Option 1: [tex]\( x = 1, y = -3, z = -1 \)[/tex]

[tex]\[ 6(1) - (-3) + 3(-1) = 6 + 3 - 3 = 6 \quad (\text{Not equal to } 12) \][/tex]

Option 2: [tex]\( x = 1, y = -3, z = 1 \)[/tex]

[tex]\[ 6(1) - (-3) + 3(1) = 6 + 3 + 3 = 12 \quad (\text{Correct}) \][/tex]

Option 3: [tex]\( x = 1, y = 3, z = 19 \)[/tex]

[tex]\[ 6(1) - (3) + 3(19) = 6 - 3 + 57 = 60 \quad (\text{Not equal to } 12) \][/tex]

Option 4: [tex]\( x = 1, y = 3, z = -2 \)[/tex]

[tex]\[ 6(1) - 3 + 3(-2) = 6 - 3 - 6 = -3 \quad (\text{Not equal to } 12) \][/tex]

### Step 3: Verify the Equation 3

Substituting the given values into the third equation:
[tex]\[ 8x + 2y + 4z = 6 \][/tex]

Option 1: [tex]\( x = 1, y = -3, z = -1 \)[/tex]

[tex]\[ 8(1) + 2(-3) + 4(-1) = 8 - 6 - 4 = -2 \quad (\text{Not equal to } 6) \][/tex]

Option 2: [tex]\( x = 1, y = -3, z = 1 \)[/tex]

[tex]\[ 8(1) + 2(-3) + 4(1) = 8 - 6 + 4 = 6 \quad (\text{Correct}) \][/tex]

Option 3: [tex]\( x = 1, y = 3, z = 19 \)[/tex]

[tex]\[ 8(1) + 2(3) + 4(19) = 8 + 6 + 76 = 90 \quad (\text{Not equal to } 6) \][/tex]

Option 4: [tex]\( x = 1, y = 3, z = -2 \)[/tex]

[tex]\[ 8(1) + 2(3) + 4(-2) = 8 + 6 - 8 = 6 \quad (\text{Correct}) \][/tex]

### Conclusion

The solution that satisfies all three equations is:
[tex]\[ (x, y, z) = (1, -3, 1) \][/tex]

Thus, the correct solution to the system of linear equations is:
[tex]\[ x = 1, \quad y = -3, \quad z = 1 \][/tex]