Question

Find the adjoint of the matrix
3 24
A=1202
2
4 2 3​

Answer 1

Answer:

Let A=[

1

3

2

4

]

We know that adjA=C

T

So, let's find cofactors of each of the elements of A.

C

11

=(−1)

1+1

4=4

C

12

=(−1)

1+2

3=−3

C

21

=(−1)

2+1

2=−2

C

22

=(−1)

2+2

1=1

So, cofactor matrix is C=[

4

−2

−3

1

]

⇒C

T

=[

4

−3

−2

1

]

Hence, adjA=[

4

−3

−2

1

]