7.

Find a solution to the following system of equations.
−2x + y = −3
−x + 2y = 3

(–21, –9)

(3, 3)

(0, 2)

(–3, –9)

1 answer

To find a solution for the given system of equations:

1. \( -2x + y = -3 \)
2. \( -x + 2y = 3 \)

we can use either the substitution method or the elimination method. Here, we'll use the elimination method.

First, let's multiply the second equation by 2 to make the coefficients of \(y\) the same in both equations:

2. \( -2x + 4y = 6 \)

Let's now write both equations:

1. \( -2x + y = -3 \)
2. \( -2x + 4y = 6 \)

Next, subtract equation 1 from equation 2 to eliminate \(x\):

\[
(-2x + 4y) - (-2x + y) = 6 - (-3)
\]

This simplifies to:

\[
4y - y = 6 + 3
\]

\[
3y = 9
\]

\[
y = 3
\]

Now that we have \(y = 3\), we can substitute \(y\) back into one of the original equations to solve for \(x\). We'll use the first equation:

\[
-2x + y = -3
\]

Substitute \(y = 3\):

\[
-2x + 3 = -3
\]

Subtract 3 from both sides:

\[
-2x = -6
\]

Divide by -2:

\[
x = 3
\]

So the solution to the system of equations is \((x, y) = (3, 3)\).

Therefore, the correct option is:
\[
(3, 3)
\]