Given [tex]\(\left[\begin{array}{ll}12 & -13 \\ 17 & -22\end{array}\right]\left[\begin{array}{l}x \\ y\end{array}\right]=\left[\begin{array}{c}7 \\ -51\end{array}\right]\)[/tex], what is [tex]\(\left|A_y\right|\)[/tex]?

A. [tex]\(\left|\begin{array}{cc}7 & -13 \\ -51 & -22\end{array}\right|\)[/tex]

B. [tex]\(\left|\begin{array}{cc}12 & 7 \\ 17 & -51\end{array}\right|\)[/tex]

C. [tex]\(\left|\begin{array}{cc}7 & -51 \\ 17 & -22\end{array}\right|\)[/tex]

D. [tex]\(\left|\begin{array}{ll}12 & -13 \\ 7 & -51\end{array}\right|\)[/tex]



Answer :

To solve the given problem, we need to determine the value of [tex]\(\left|A_y\right|\)[/tex].

Given the matrix equation:

[tex]\[ \left[\begin{array}{ll}12 & -13 \\ 17 & -22\end{array}\right]\left[\begin{array}{l}x \\ y\end{array}\right]=\left[\begin{array}{c}7 \\ -51\end{array}\right] \][/tex]

We need to identify the matrix whose determinant is requested. The matrix associated with the notation [tex]\(\left|A_y\right|\)[/tex] corresponds to the column of constants replacing the [tex]\(y\)[/tex]-column of the original matrix. As stated in the problem, we need [tex]\(\left|A_y\right|\)[/tex].

Replacing the [tex]\(y\)[/tex]-column ([tex]\([-13, -22]\)[/tex]) with the constants vector ([tex]\([7, -51]\)[/tex]), we get the augmented matrix:

[tex]\[ \left[\begin{array}{cc} 12 & 7 \\ 17 & -51 \end{array}\right] \][/tex]

However, the task is to identify the correct matrix from the provided ones. Among these matrices, the matching structure, where the [tex]\(y\)[/tex]-column is replaced by the constants is:

[tex]\[ \left[\begin{array}{cc} 7 & -51 \\ 17 & -22 \end{array}\right]. \][/tex]

So, our focus is on the matrix:

[tex]\[ \left[\begin{array}{cc} 7 & -51 \\ 17 & -22 \end{array}\right] \][/tex]

To determine [tex]\(\left|A_y\right|\)[/tex], we find the determinant of this matrix. The determinant for a 2x2 matrix [tex]\(\left[\begin{array}{cc} a & b \\ c & d \end{array}\right]\)[/tex] is given by:

[tex]\[ \left| \begin{array}{cc} 7 & -51 \\ 17 & -22 \end{array}\right| = 7 \cdot (-22) - (-51) \cdot 17 = -154 + 867 = 713. \][/tex]

Thus, the determinant [tex]\(\left|A_y\right|\)[/tex] is:

[tex]\[ \boxed{713}. \][/tex]

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