What is the solution to this system of equations using the linear combination method?

[tex]\[
\left\{\begin{array}{l}
5x + y = 2 \\
4x + y = 5
\end{array}\right.
\][/tex]

A. [tex]\((0,2)\)[/tex]
B. [tex]\((-3,17)\)[/tex]
C. [tex]\((1,-8)\)[/tex]
D. [tex]\((-2,12)\)[/tex]



Answer :

To solve the given system of equations using the linear combination (or elimination) method, follow these steps:

Given the system:
[tex]\[ \begin{cases} 5x + y = 2 \\ 4x + y = 5 \end{cases} \][/tex]

1. Formulate the system of equations:
[tex]\[ \begin{aligned} 1. & \quad 5x + y = 2 \quad \text{(Equation 1)} \\ 2. & \quad 4x + y = 5 \quad \text{(Equation 2)} \end{aligned} \][/tex]

2. Eliminate one variable (y):
- Subtract Equation 2 from Equation 1 to eliminate [tex]\( y \)[/tex].
[tex]\[ (5x + y) - (4x + y) = 2 - 5 \][/tex]

3. Simplify the resulting equation to solve for [tex]\( x \)[/tex]:
[tex]\[ 5x + y - 4x - y = 2 - 5 \][/tex]
[tex]\[ x = -3 \][/tex]

4. Substitute [tex]\( x = -3 \)[/tex] back into one of the original equations to solve for [tex]\( y \)[/tex]:
- Using Equation 1:
[tex]\[ 5(-3) + y = 2 \][/tex]
[tex]\[ -15 + y = 2 \][/tex]
[tex]\[ y = 2 + 15 \][/tex]
[tex]\[ y = 17 \][/tex]

Hence, the solution to the system of equations is:
[tex]\[ (x, y) = (-3, 17) \][/tex]

This matches the solution provided in the multiple-choice options:
[tex]\[ (-3, 17) \][/tex]

Therefore, the correct choice is:
[tex]\[ \boxed{(-3, 17)} \][/tex]