Study guide and 5 practice problems on:

## Minor and cofactor expansions

The minor of the $(i,j)$th entry of a matrix $\bfA$ is the determinant of the submatrix obtained by removing the $i$th row and the $j$th column of $\bfA$.
To compute a determinant by the a minor and cofactor expansion:
1. Choose a row or column.

2. For each entry in that row or column, form the minor by removing its entire row and column
3. Form the sum of each entry with the its minor. Make sure the signs of each term follow a checkerboard pattern