Question 6 (Multiple Choice Worth 1 point)

Solve the system of equations using substitution.
[tex]\[
\begin{array}{l}
3x + 2y = 7 \\
x = 3y + 6
\end{array}
\][/tex]

A. (0, -2)
B. (1, 2)
C. (3, -1)
D. (6, 0)



Answer :

To solve the system of equations using substitution, let’s follow a step-by-step approach:

First, let’s write down the given system of equations:
[tex]\[ 3x + 2y = 7 \][/tex]
[tex]\[ x = 3y + 6 \][/tex]

1. Substitute the value of [tex]\( x \)[/tex] from the second equation into the first equation.

Given [tex]\( x = 3y + 6 \)[/tex], substitute this into the first equation:
[tex]\[ 3(3y + 6) + 2y = 7 \][/tex]

2. Simplify the equation:
[tex]\[ 9y + 18 + 2y = 7 \][/tex]

3. Combine like terms:
[tex]\[ 11y + 18 = 7 \][/tex]

4. Isolate the term with [tex]\( y \)[/tex] by subtracting 18 from both sides of the equation:
[tex]\[ 11y = 7 - 18 \][/tex]
[tex]\[ 11y = -11 \][/tex]

5. Solve for [tex]\( y \)[/tex] by dividing both sides by 11:
[tex]\[ y = -1 \][/tex]

6. Now, substitute [tex]\( y = -1 \)[/tex] back into the second original equation to solve for [tex]\( x \)[/tex]:
[tex]\[ x = 3(-1) + 6 \][/tex]
[tex]\[ x = -3 + 6 \][/tex]
[tex]\[ x = 3 \][/tex]

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

7. Verify this solution with the potential choices given:
[tex]\[ (0, -2), (1, 2), (3, -1), (6, 0) \][/tex]

The pair [tex]\((3, -1)\)[/tex] matches our solution.

Therefore, the correct choice is:
[tex]\[ (3, -1) \][/tex]