The concept of determinant originates from the solution of linear equations. It is derived from the solution formula of binary and ternary linear equations.

Concept

Principal Diagonal: Diagonal line composed of upper left and lower right.

Subdiagonal: Another diagonal.

Diagonal expansion:

|a1 b1| =a1b2-a2b1

|a2 b2|

|a1 b1 c1|

|a2 b2 c2|=a1b2c3+b1c2a3+c1a2b3-a3b2c1-b3c2a1-c3a2b1

|a3 b3 c3|