Question

Determine all minors and cofactors of the matrix A given below (5)

2 −1 1 3

0 1 1 3

2 1 1 0

2 0 −1 −2


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Answer 1

So, there i a LOT of calculating to do here. I will try to summarize:

A minor of a matrix A is the determinant of some smaller square matrix, cut down from A by removing one or more of its rows and columns.

E.g the minor for a_11 is the matrix
1 1 3
1 1 0
0 -1 -2

The cofactor of an element is the minor but a factor, with that factor being (-1)^(i+j) where i and j are the row and column of the element