Question

Help please!!!!!!!!!

Answer 1

24

Step-by-step explanation

For a matrix A of order n×n, the cofactor
`C_(ij)` of element
`a_(ij)` is defined to be

`C_(ij) = (-1)^(i+j) M_(ij)`

`M_(ij)` is the minor of element
`a_(ij)` equal to the determinant of the matrix we get by taking matrix A and deleting row i and column j.

Here, we have

`C_(11) = (-1)^(1+1) M_(11) = M_(11)`

M₁₁ is the determinant of the matrix that is matrix A with row 1 and column 1 removed. The bold entries are the row and the column we delete.

Since the determinant of a 2×2 matrix is

`image`

it follows that

so
`C_(11) = M_(11) = 24`