Select the correct augmented matrices.

Liam wants to buy a car and pay for it in three installments. The total cost of the car is [tex]\$29,000[/tex]. Two times the first installment is [tex]\$1,000[/tex] more than the sum of the third installment and three times the second installment. Liam must pay 15% interest on the second and the third installments; the interest will amount to [tex]\$2,100[/tex]. If [tex]x[/tex], [tex]y[/tex], and [tex]z[/tex] represent the first, second, and third installments, respectively, identify the augmented matrices that model Liam's situation.

\[
\begin{array}{ll}
\left[
\begin{array}{ccc|r}
1 & 1 & 1 & 29000 \\
2 & -3 & -1 & 1000 \\
0.15 & 0.15 & 0.15 & 2100
\end{array}
\right] &
\left[
\begin{array}{rrr|r}
1 & 1 & 1 & 29000 \\
-3 & 2 & 0 & -15000 \\
0 & 1 & 1 & 14000
\end{array}
\right] \\
\left[
\begin{array}{ccc|r}
1 & 1 & 1 & 29000 \\
2 & -3 & -1 & 1000 \\
0 & 0.15 & 0.15 & 2100
\end{array}
\right] &
\left[
\begin{array}{rrr|r}
1 & 0 & 0 & 15000 \\
0 & 1 & 0 & 7500 \\
0 & 0 & 1 & 6500
\end{array}
\right] \\
\left[
\begin{array}{rrr|r}
1 & 0 & 0 & 15000 \\
0 & 1 & 0 & 8500 \\
0 & 0 & 1 & 5500
\end{array}
\right]
\end{array}
\]

Answer :

We begin by defining the variables as follows:

- Let [tex]\( x \)[/tex] be the first installment.
- Let [tex]\( y \)[/tex] be the second installment.
- Let [tex]\( z \)[/tex] be the third installment.

The problem gives us three conditions:

1. The total cost of the car is \[tex]$29,000. This yields:
$[/tex][tex]$
x + y + z = 29000.
$[/tex][tex]$

2. Two times the first installment is \$[/tex]1,000 more than the sum of the third installment and three times the second installment. In equation form, we have:
[tex]$$
2x = z + 3y + 1000.
$$[/tex]
Rearranging the equation by subtracting [tex]\( 3y \)[/tex] and [tex]\( z \)[/tex] from both sides, we obtain:
[tex]$$
2x - 3y - z = 1000.
$$[/tex]

3. Liam must pay 15% interest on the second and the third installments, and this interest amounts to \[tex]$2,100. The interest on \( y \) and \( z \) is given by:
$[/tex][tex]$
0.15y + 0.15z = 2100.
$[/tex][tex]$

The augmented matrix representing these three equations is constructed by writing the coefficients of \( x \), \( y \), and \( z \) in each equation along with the constant term. Thus, the augmented matrix is:

$[/tex][tex]$
\left[\begin{array}{ccc|r}
1 & 1 & 1 & 29000 \\
2 & -3 & -1 & 1000 \\
0 & 0.15 & 0.15 & 2100
\end{array}\right].
$[/tex]$

This is the correct augmented matrix that models Liam's situation.