Find the inverse of the matrix below. If necessary, round to the nearest hundredth.

[tex]\[
\left[\begin{array}{cc}
-6 & -12 \\
-9 & -16
\end{array}\right]
\][/tex]



Answer :

To find the inverse of the given matrix, we start with the following 2x2 matrix:

[tex]\[ A = \begin{pmatrix} -6 & -12 \\ -9 & -16 \end{pmatrix} \][/tex]

The formula for the inverse of a 2x2 matrix

[tex]\[ A = \begin{pmatrix} a & b \\ c & d \end{pmatrix} \][/tex]

is:

[tex]\[ A^{-1} = \frac{1}{ad - bc} \begin{pmatrix} d & -b \\ -c & a \end{pmatrix} \][/tex]

In our case:

[tex]\[ a = -6, \quad b = -12, \quad c = -9, \quad d = -16 \][/tex]

First, calculate the determinant of [tex]\(A\)[/tex]:

[tex]\[ \text{det}(A) = (-6)(-16) - (-12)(-9) \][/tex]

[tex]\[ \text{det}(A) = 96 - 108 = -12 \][/tex]

Since the determinant is non-zero, the inverse of the matrix exists. Next, use the formula to find the inverse:

[tex]\[ A^{-1} = \frac{1}{-12} \begin{pmatrix} -16 & 12 \\ 9 & -6 \end{pmatrix} \][/tex]

Now, multiply each element of the matrix by [tex]\(\frac{1}{-12}\)[/tex]:

[tex]\[ A^{-1} = \begin{pmatrix} \frac{-16}{-12} & \frac{12}{-12} \\ \frac{9}{-12} & \frac{-6}{-12} \end{pmatrix} \][/tex]

Simplify the fractions:

[tex]\[ A^{-1} = \begin{pmatrix} \frac{4}{3} & -1 \\ -\frac{3}{4} & \frac{1}{2} \end{pmatrix} \][/tex]

Next, convert the fractions to decimals and round to the nearest hundredth if necessary:

[tex]\[ \frac{4}{3} \approx 1.33, \quad -1 \text{ remains } -1, \quad -\frac{3}{4} = -0.75, \quad \frac{1}{2} = 0.5 \][/tex]

Thus, the inverse matrix rounded to the nearest hundredth is:

[tex]\[ A^{-1} = \begin{pmatrix} 1.33 & -1 \\ -0.75 & 0.5 \end{pmatrix} \][/tex]

Hence, the inverse of the matrix

[tex]\[ \begin{pmatrix} -6 & -12 \\ -9 & -16 \end{pmatrix} \][/tex]

is

[tex]\[ \boxed{\begin{pmatrix} 1.33 & -1 \\ -0.75 & 0.5 \end{pmatrix}} \][/tex]