Solve the system by substitution. If the system is inconsistent or has dependent equations, say so.

[tex]\[
\begin{aligned}
-x - 2y &= -8 \\
y &= 6x - 9
\end{aligned}
\][/tex]



Answer :

Certainly! Let's solve the system of linear equations by substitution.

The given system of equations is:
[tex]\[ \begin{aligned} -x - 2y &= -8 \quad \text{(1)} \\ y &= 6x - 9 \quad \text{(2)} \end{aligned} \][/tex]

We can use the substitution method as follows:

1. Solve one of the equations for one variable.

Equation (2) is already solved for [tex]\( y \)[/tex]:
[tex]\[ y = 6x - 9 \][/tex]

2. Substitute this expression into the other equation.

Substitute [tex]\( y = 6x - 9 \)[/tex] into Equation (1):
[tex]\[ -x - 2(6x - 9) = -8 \][/tex]

3. Simplify and solve for [tex]\( x \)[/tex].
[tex]\[ -x - 2(6x - 9) = -8 \][/tex]
Distribute the [tex]\(-2\)[/tex]:
[tex]\[ -x - 12x + 18 = -8 \][/tex]
Combine like terms:
[tex]\[ -13x + 18 = -8 \][/tex]
Subtract 18 from both sides:
[tex]\[ -13x = -8 - 18 \][/tex]
Simplify the right side:
[tex]\[ -13x = -26 \][/tex]
Divide by [tex]\(-13\)[/tex]:
[tex]\[ x = \frac{-26}{-13} = 2 \][/tex]

4. Substitute [tex]\( x \)[/tex] back into the expression for [tex]\( y \)[/tex].
[tex]\[ y = 6x - 9 \][/tex]
Substitute [tex]\( x = 2 \)[/tex]:
[tex]\[ y = 6(2) - 9 = 12 - 9 = 3 \][/tex]

So, the solution to the system of equations is:
[tex]\[ (x, y) = (2, 3) \][/tex]

Verification:

To verify, substitute [tex]\( x = 2 \)[/tex] and [tex]\( y = 3 \)[/tex] back into the original equations:

For Equation (1):
[tex]\[ -x - 2y = -8 \][/tex]
[tex]\[ -(2) - 2(3) = -8 \][/tex]
[tex]\[ -2 - 6 = -8 \][/tex]
[tex]\[-8 = -8 \quad \text{(True)}\][/tex]

For Equation (2):
[tex]\[ y = 6x - 9 \][/tex]
\]
[tex]\[ 3 = 6(2) - 9 =1]} \][/tex]
\+9}
[tex]\[ 3 = 12 - 9 \][/tex]
3
\]
{-9}

Both equations are satisfied with [tex]\( x = 2 \)[/tex] and [tex]\( y = 3 \)[/tex], confirming our solution is correct.

Thus, the solution to the system is:

[tex]\[ (x, y) = (2, 3) \][/tex]