Letβs look at what are minors & cofactor of a 2 Γ 2 & a 3 Γ 3 determinant
Β
For a 2 Γ 2 determinant
For
We have elements,
Β Β π
11
= 3
Β Β π
12
= 2
Β Β π
21
= 1
Β Β π
22
= 4
Β
Minor will be
π 11 ,Β π 12 ,Β π 21 ,Β π 22
And cofactors will be
π΄ 11 ,Β π΄ 12 ,Β π΄ 21 ,Β π΄ 22
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For a 3 Γ 3 matrix
Β
Minor will be
M 11 , M 12 , M 13 , M 21 , M 22 , M 23 , M 31 , M 32 , M 33
Note : We can also calculate cofactors without calculating minors
If i + j is odd,
A ij = β1 Γ M ij
If i + j is even,
A ij = M ij
But, why use cofactor?
Β
Β
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