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Solve the following system of equations:

[tex]\[
\begin{array}{l}
-x - 5y = -2 \\
2x + 3y = 18
\end{array}
\][/tex]

Sagot :

To solve the given system of linear equations:

[tex]\[ \begin{array}{l} -x - 5y = -2 \quad \text{(1)} \\ 2x + 3y = 18 \quad \text{(2)} \end{array} \][/tex]

we can use the method of substitution or elimination. Here, let's use the elimination method to find the solution step-by-step.

First, we will eliminate one of the variables by making the coefficients of either [tex]\( x \)[/tex] or [tex]\( y \)[/tex] the same (or additive inverses) in both equations. Let's choose to eliminate [tex]\( x \)[/tex].

We have:
[tex]\[ -x - 5y = -2 \quad \text{(Equation 1)} \][/tex]
[tex]\[ 2x + 3y = 18 \quad \text{(Equation 2)} \][/tex]

To eliminate [tex]\( x \)[/tex], we can multiply the first equation by 2, so that the coefficients of [tex]\( x \)[/tex] in both equations are opposites:

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

This simplifies to:
[tex]\[ -2x - 10y = -4 \quad \text{(Equation 3)} \][/tex]

Now, we can add Equation 3 to Equation 2 to eliminate [tex]\( x \)[/tex]:

[tex]\[ -2x - 10y = -4 \quad \text{(Equation 3)} \][/tex]
[tex]\[ 2x + 3y = 18 \quad \text{(Equation 2)} \][/tex]

Adding these two equations together, we get:

[tex]\[ (-2x + 2x) + (-10y + 3y) = -4 + 18 \][/tex]

This simplifies to:
[tex]\[ 0x - 7y = 14 \][/tex]

So, we have:
[tex]\[ -7y = 14 \][/tex]

Solving for [tex]\( y \)[/tex]:
[tex]\[ y = \frac{14}{-7} \][/tex]
[tex]\[ y = -2 \][/tex]

Now that we have the value of [tex]\( y \)[/tex], we can substitute it back into one of the original equations to find [tex]\( x \)[/tex]. Let's substitute [tex]\( y = -2 \)[/tex] into Equation 1:

[tex]\[ -x - 5(-2) = -2 \][/tex]

This simplifies to:
[tex]\[ -x + 10 = -2 \][/tex]

Subtracting 10 from both sides, we get:
[tex]\[ -x = -2 - 10 \][/tex]
[tex]\[ -x = -12 \][/tex]

Multiplying both sides by -1, we get:
[tex]\[ x = 12 \][/tex]

Therefore, the solution to the system of equations is:
[tex]\[ x = 12 \][/tex]
[tex]\[ y = -2 \][/tex]

So, the solution is [tex]\( (12, -2) \)[/tex].