Find the inverse of the matrix:

[tex]\[
\left(\begin{array}{lll}
1 & 1 & 1 \\
0 & 1 & 2 \\
1 & 0 & 1
\end{array}\right)^{-1}
\][/tex]



Answer :

To find the inverse of the matrix

[tex]\[ \begin{pmatrix} 1 & 1 & 1 \\ 0 & 1 & 2 \\ 1 & 0 & 1 \end{pmatrix}, \][/tex]

we can follow these steps:

1. Determine the determinant of the matrix: This is essential as it's a requirement for the matrix to be invertible. The determinant must be non-zero.

2. Find the matrix of minors: Calculate the determinant of the 2x2 minor matrices for each element in the original matrix.

3. Find the matrix of cofactors: Apply a checkerboard pattern of plus and minus signs to the matrix of minors.

4. Transpose the matrix of cofactors: This forms the adjugate (or adjoint) of the matrix.

5. Divide each element by the determinant: This will yield the inverse of the original matrix.

However, I will directly provide you with the result obtained from the inverse calculation:

The inverse of the matrix

[tex]\[ \begin{pmatrix} 1 & 1 & 1 \\ 0 & 1 & 2 \\ 1 & 0 & 1 \end{pmatrix} \][/tex]

is

[tex]\[ \begin{pmatrix} 0.5 & -0.5 & 0.5 \\ 1 & 0 & -1 \\ -0.5 & 0.5 & 0.5 \end{pmatrix}. \][/tex]