Solving Systems Using Gaussian Elimination: Mastery Test

A veterinarian is mixing three different types of feed to produce a mixture that contains 44 grams of fat, 48 grams of carbohydrates, and 132 grams of protein.

- Each serving of the first type of feed, [tex]$x$[/tex], contains 11 grams of fat, 24 grams of carbs, and 3 grams of protein.
- Each serving of the second type of feed, [tex]$y$[/tex], contains 4 grams of fat, 8 grams of carbs, and 31 grams of protein.
- Each serving of the third type of feed, [tex][tex]$z$[/tex][/tex], contains 10 grams of fat, 0 grams of carbs, and 18 grams of protein.

Which matrix represents the system of equations that will give the number of servings of each type of feed the veterinarian should include?

A. [tex]\left[\begin{array}{ccc|c}11 & 4 & 10 & 44 \\ 24 & 8 & 0 & 48 \\ 3 & 31 & 18 & 132\end{array}\right][/tex]
B. [tex]\left[\begin{array}{ccc}11 & 4 & 10 \\ 24 & 8 & 0 \\ 3 & 31 & 18\end{array}\right][/tex]
C. [tex]\left[\begin{array}{ccc|c}11 & 4 & 10 & 3 \\ 24 & 8 & 0 & 31 \\ 44 & 48 & 132 & 18\end{array}\right][/tex]
D. [tex]\left[\begin{array}{ccc|c}11 & 24 & 3 & 44 \\ 4 & 8 & 31 & 48 \\ 10 & 0 & 18 & 132\end{array}\right][/tex]



Answer :

To determine the correct matrix representation for the system of equations, let's first establish the system based on the given information. We have three equations with three variables [tex]\( x \)[/tex], [tex]\( y \)[/tex], and [tex]\( z \)[/tex], representing the servings of each type of feed. The equations are derived from the grams of fat, carbohydrates, and protein each type of feed provides:

1. Fat equation:
[tex]\[ 11x + 4y + 10z = 44 \][/tex]

2. Carbohydrate equation:
[tex]\[ 24x + 8y = 48 \][/tex]

3. Protein equation:
[tex]\[ 3x + 31y + 18z = 132 \][/tex]

We want to represent this system in a matrix form, specifically an augmented matrix, which includes the coefficients of [tex]\( x \)[/tex], [tex]\( y \)[/tex], and [tex]\( z \)[/tex], as well as the constants on the right side of the equations.

Firstly, let's put down the matrix elements systematically from the equations:
- The coefficients from the fat equation provide the first row.
- The coefficients from the carbohydrate equation give us the second row.
- The coefficients from the protein equation result in the third row.

Thus, the augmented matrix is:
[tex]\[ \left[\begin{array}{ccc|c} 11 & 4 & 10 & 44 \\ 24 & 8 & 0 & 48 \\ 3 & 31 & 18 & 132 \end{array}\right] \][/tex]

We now compare this matrix to the options provided:
- Option A is exactly:
[tex]\[ \left[\begin{array}{ccc|c} 11 & 4 & 10 & 44 \\ 24 & 8 & 0 & 48 \\ 3 & 31 & 18 & 132 \end{array}\right] \][/tex]

- Option B is missing the constants on the right side of the augmented matrix, so it cannot be the correct representation:
[tex]\[ \left[\begin{array}{ccc} 11 & 4 & 10 \\ 24 & 8 & 0 \\ 3 & 31 & 18 \end{array}\right] \][/tex]

- Option C has incorrect values for the constants on the right side:
[tex]\[ \left[\begin{array}{ccc|c} 11 & 4 & 10 & 3 \\ 24 & 8 & 0 & 31 \\ 44 & 48 & 132 & 18 \end{array}\right] \][/tex]

- Option D has the mixed order of coefficients and thus does not represent the actual system:
[tex]\[ \left[\begin{array}{ccc|c} 11 & 24 & 3 & 44 \\ 4 & 8 & 31 & 48 \\ 10 & 0 & 18 & 132 \end{array}\right] \][/tex]

Therefore, the correct matrix that represents the system of equations is Option A.