Solve the system of equations:
[tex]\[
\begin{array}{l}
3x + 7y = 1 \\
y = x - 7
\end{array}
\][/tex]

A. [tex]\((2, -5)\)[/tex]
B. [tex]\((5, -2)\)[/tex]
C. [tex]\((4, -3)\)[/tex]
D. [tex]\((3, -4)\)[/tex]



Answer :

To solve the system of linear equations:

[tex]\[ \begin{cases} 3x + 7y = 1 \\ y = x - 7 \end{cases} \][/tex]

we'll use the substitution method given that the second equation is already solved for [tex]\( y \)[/tex]:

1. Substitute [tex]\( y = x - 7 \)[/tex] into the first equation [tex]\( 3x + 7y = 1 \)[/tex]:

[tex]\[ 3x + 7(x - 7) = 1 \][/tex]

2. Simplify the equation to solve for [tex]\( x \)[/tex]:

[tex]\[ 3x + 7x - 49 = 1 \][/tex]

Combine like terms:

[tex]\[ 10x - 49 = 1 \][/tex]

Add 49 to both sides:

[tex]\[ 10x = 50 \][/tex]

Divide both sides by 10:

[tex]\[ x = 5 \][/tex]

3. Substitute [tex]\( x = 5 \)[/tex] back into the second equation [tex]\( y = x - 7 \)[/tex] to solve for [tex]\( y \)[/tex]:

[tex]\[ y = 5 - 7 \][/tex]

[tex]\[ y = -2 \][/tex]

So, the solution to the system of equations is [tex]\( (5, -2) \)[/tex].

4. Verify which option matches this solution:

[tex]\[ \begin{array}{l} A: (2, -5) \\ B: (5, -2) \\ C: (4, -3) \\ D: (3, -4) \end{array} \][/tex]

The correct answer is [tex]\( (5, -2) \)[/tex], which corresponds to.

[tex]\[ \boxed{B} \][/tex]

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