Invert these matrices A by the Gauss-Jordan method starting [AI]

Question

A = [1 0 0

2 1 3

0 0 1]

and A =[ 1 1 1

1 2 2

1 2 3 ]

Answer 1

A = [1 0 0

2 1 3

0 0 1]

Det(A) = 0, therefore no inverse

Inverse of second matrix

[2 -1 0

-1 2 -1

0 -1 1]