Question

A=|1 2 3|. Find the inverse |1 1 5|
|2 4 7|

Answer 1

Answer:

∣A∣=2×3−4×−2=14

Minors are M

11

=3 M

12

=4 M

21

=−2 M

22

=2

Cofactors are C

11

=3 C

12

=−4 C

21

=2 C

22

=2

Adj.A=[

3

−4

2

2

]

A

−1

=

∣A∣

1

Adj.A=

14

1

[

3

−4

2

2

]