Question 6 (5 points)

Find [tex]3\left[\begin{array}{cc}5 & 6 \\ -9 & -2\end{array}\right]-2\left[\begin{array}{cc}0 & 2 \\ -6 & -4\end{array}\right][/tex].

A. [tex]\left[\begin{array}{cc}15 & 14 \\ -19 & 6\end{array}\right][/tex]

B. [tex]\left[\begin{array}{cc}-5 & -4 \\ 3 & -2\end{array}\right][/tex]

C. [tex]\left[\begin{array}{cc}15 & 14 \\ -15 & 2\end{array}\right][/tex]

D. [tex]\left[\begin{array}{cc}11 & 18 \\ -19 & 6\end{array}\right][/tex]



Answer :

To find the result of the expression [tex]\(3\left[\begin{array}{cc}5 & 6 \\ -9 & -2\end{array}\right] - 2\left[\begin{array}{cc}0 & 2 \\ -6 & -4\end{array}\right]\)[/tex], let's break it down step by step.

First, we'll perform the scalar multiplication separately on each matrix.

1. Multiply the first matrix by 3:

[tex]\[ \begin{array}{cc} 5 & 6 \\ -9 & -2 \\ \end{array} \][/tex]

Multiplying each element by 3:

[tex]\[ 3 \left[\begin{array}{cc}5 & 6 \\ -9 & -2\end{array}\right] = \left[\begin{array}{cc}3 \cdot 5 & 3 \cdot 6 \\ 3 \cdot (-9) & 3 \cdot (-2)\end{array}\right] = \left[\begin{array}{cc}15 & 18 \\ -27 & -6\end{array}\right] \][/tex]

2. Multiply the second matrix by 2:

[tex]\[ \begin{array}{cc} 0 & 2 \\ -6 & -4 \\ \end{array} \][/tex]

Multiplying each element by 2:

[tex]\[ 2 \left[\begin{array}{cc}0 & 2 \\ -6 & -4\end{array}\right] = \left[\begin{array}{cc}2 \cdot 0 & 2 \cdot 2 \\ 2 \cdot (-6) & 2 \cdot (-4)\end{array}\right] = \left[\begin{array}{cc}0 & 4 \\ -12 & -8\end{array}\right] \][/tex]

3. Subtract the second matrix from the first matrix:

[tex]\[ \left[\begin{array}{cc}15 & 18 \\ -27 & -6\end{array}\right] - \left[\begin{array}{cc}0 & 4 \\ -12 & -8\end{array}\right] \][/tex]

Subtract corresponding elements:

[tex]\[ \left[\begin{array}{cc}15 - 0 & 18 - 4 \\ -27 - (-12) & -6 - (-8)\end{array}\right] = \left[\begin{array}{cc}15 & 14 \\ -15 & 2\end{array}\right] \][/tex]

Therefore, the result of the expression is:

[tex]\[ \left[\begin{array}{cc}15 & 14 \\ -15 & 2\end{array}\right] \][/tex]

So, the correct option is:

[tex]\[ \left[\begin{array}{cc}15 & 14 \\ -15 & 2\end{array}\right] \][/tex]