Dylan's Blog

I wasn't at school for three days. Blah. I did get the last few notes though.

Determinate's for 3x3 matrices:

1. pick a row r1->most 0s or 1s
2. delete row, delete column
3. repeat for other columns

ex.
|0 3 4|
|2 9 1|
|6 2 1|

this would become

|0 3 4|
|2 9 1|
|6 2 1| x=deleted

this leaves:
|2 9|
|6 2|

Now for the others:

|2 1|
|6 1|

&

|9 1|
|2 1|

Next you take the first number of the row and multiply by the matrix by the number:
|2 9|
|6 2|

|0 3 4|
|2 9 1|
|6 2 1|

4 would be the number used to multiply the matrix

4|2 9|
|6 2|
=
-200 (use ad-bc to find the matrix)

repeat for others, and you should get
0+24-200=-176