Minor of an Element

The minor of an element in a determinant is found by deleting the entire row and the entire column that the element sits in, and taking the determinant of whatever remains. If an element lies in the $i$-th row and $j$-th column, its minor is denoted $M_{ij}$ — the determinant of the smaller matrix left behind once that row and column are struck out. For a $3 \times 3$ determinant, every minor is itself a $2 \times 2$ determinant, whi …