What is the solution to the system of equations?

[tex]\[
\left\{
\begin{array}{l}
7x + 3y = -11 \\
2x + 5y = 1
\end{array}
\right.
\][/tex]

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



Answer :

To determine the solution to the given system of equations:

[tex]\[ \begin{cases} 7x + 3y = -11 \\ 2x + 5y = 1 \end{cases} \][/tex]

we will follow these steps:

1. Write down the system of linear equations:

[tex]\[ 7x + 3y = -11 \quad \text{(Equation 1)} \][/tex]

[tex]\[ 2x + 5y = 1 \quad \text{(Equation 2)} \][/tex]

2. Choose one of the substitution or elimination methods to solve the system. In this case, let's use the elimination method to eliminate [tex]\( y \)[/tex].

3. Multiply Equation 1 by 5 and Equation 2 by 3 so that the coefficients of [tex]\( y \)[/tex] will be the same:

[tex]\[ \begin{cases} 5 \cdot (7x + 3y) = 5 \cdot (-11) \\ 3 \cdot (2x + 5y) = 3 \cdot 1 \end{cases} \][/tex]

which simplifies to:

[tex]\[ \begin{cases} 35x + 15y = -55 \\ 6x + 15y = 3 \end{cases} \][/tex]

4. Subtract the second equation from the first to eliminate [tex]\( y \)[/tex]:

[tex]\[ (35x + 15y) - (6x + 15y) = -55 - 3 \][/tex]

This simplifies to:

[tex]\[ 29x = -58 \][/tex]

5. Solve for [tex]\( x \)[/tex]:

[tex]\[ x = \frac{-58}{29} = -2 \][/tex]

6. Substitute [tex]\( x = -2 \)[/tex] back into one of the original equations (let's use Equation 2) to find [tex]\( y \)[/tex]:

[tex]\[ 2(-2) + 5y = 1 \][/tex]

This simplifies to:

[tex]\[ -4 + 5y = 1 \][/tex]

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

[tex]\[ y = 1 \][/tex]

Thus, the solution to the system of equations is [tex]\( (x, y) = (-2, 1) \)[/tex].

To check our solution against the provided choices:
- [tex]\( (3, -1) \)[/tex]
- [tex]\( (2, 1) \)[/tex]
- [tex]\( (-2, 1) \)[/tex]
- [tex]\( (1, -2) \)[/tex]

We observe that the correct solution [tex]\( (-2, 1) \)[/tex] matches one of the choices provided. Therefore, the solution to the system of equations is:

[tex]\[ \boxed{(-2, 1)} \][/tex]