Find the inverse of the matrix

[1 2 3 1]

The given matrix is [1 2 3 1].

To find the inverse of the matrix, we need to use the formula for a 2x2 matrix:

[A B]
[C D]

The inverse matrix is given by:

1/(AD - BC) * [D -B]
[-C A]

In this case, A=1, B=2, C=3, and D=1.

So the inverse matrix is:

1/(1(1) - 2(3)) * [1 -2]
[-3 1]

Simplifying further:

1/(-5) * [1 -2]
[-3 1]

The inverse of the given matrix is:

[-1/5 2/5]
[ 3/5 -1/5]

To find the inverse of a matrix, you can use the following formula:

If A is the given matrix, and A^-1 is its inverse matrix, then:

A * A^-1 = I

Here, I represents the identity matrix.

Now, let's find the inverse of the matrix you provided:

[1 2 3 1]

The given matrix has four columns, so we are looking for a 4x4 inverse matrix.

To begin, we will augment the given matrix with the identity matrix of the same size:

[1 2 3 1 | 1 0 0 0]
[.............|.............]
[.............|.............]
[.............|.............]

Perform row operations to transform the given matrix into the identity matrix.

First, divide the first row by 1:

[1 2 3 1 | 1 0 0 0]
[.............|.............]
[.............|.............]
[.............|.............]

Next, replace the second row with the second row minus twice the first row:

[1 2 3 1 | 1 0 0 0]
[0 -2 -3 -1 | 0 1 0 0]
[.............|.............]
[.............|.............]

Then, replace the third row with the third row minus three times the first row:

[1 2 3 1 | 1 0 0 0]
[0 -2 -3 -1 | 0 1 0 0]
[0 0 0 0 | 0 0 1 0]
[.............|.............]

Lastly, replace the fourth row with the fourth row minus the first row:

[1 2 3 1 | 1 0 0 0]
[0 -2 -3 -1 | 0 1 0 0]
[0 0 0 0 | 0 0 1 0]
[0 0 0 0 | 0 0 0 1]

Now, the augmented matrix has been transformed into the identity matrix. The right-hand side of the augmented matrix is the inverse of the given matrix.

Therefore, the inverse of the matrix:

[1 2 3 1]
is:

[1 0 0 0]
[0 1 0 0]
[0 0 1 0]
[0 0 0 1]