The tutor defines cofactor (aka signed minor) with an example.
In my post from Nov 24, 2014 I tell how to evaluate a determinant by hand.
Example: Evaluate the determinant of matrix A:
If the determinant is calculated from the top row, as follows
1[-1] + 0 -7[-6]
The numbers in red are called the cofactors or signed minors.
Cofactor Cmn is calculated as follows:
- Remove row m and column n.
- Calculate the determinant of the resultant matrix.
- Multiply that number by (-1)m+n
For every term in the matrix there is a signed minor.
I’ll be talking more about this:)
Johnson/Reiss/Arnold. Introduction to Linear Algebra. Don Mills: Addison-Wesley, 1989.
Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.