Determinants

Determinates

When you see a || around matrix, it is telling you to find the determinant. 

Finding a determinant is the same thing as finding the absolute value of a matrix.

Singular Matrix: when the determinant is equal to zero and it does not have an inverse.  

2x2 Matrix Formula: ad-bc 

3x3 Matrix Formula: Recopy the first 2 columns then multiply all the diagonals and add the ones on the right and subtract the ones on the left. 

Example 1:

(4 1)

(2 3) 

=4(3)-1(2)

=12-2

=10

Example 2:
(5 1)
(3 2)
=5(2)-1(3)
=10-3
=7