Determinants

~Notation- | | kind of like absolute value

~If the determinant =0 then it is called a singular matrix because it doesn't have an inverse.

~For a 2X2 matrix the formula is ad-bc

~For a 3X3 matrix - recopy the first 2 columns, then multiply the diagonals add the right, subtract the left

~For a 4X4 matrix it may be easier to just use your calculator.
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Ex.1:
find the determinant of:
|4 6|
|3 7|
4(7)-6(3)=10

Ex.2:
find the determinant of:
|5 4 8|
|0 3 7|=-36
|1 2 2|

Ex.3:
find the determinant of:
|2 4 7 9|
|6 5 1 0|=638
|1 9 6 8|
|2 8 5 9|

Ex.4:
find the determinant of:
|7 4|=-12
|3 0|

Ex.5:
find the determinant of:
|7 5 1|
|4 8 3|=118
|3 7 6|

Ex.6:
find the determinant of:
|8 9 6 5|
|5 8 4 3|=-112
|0 1 6 7|
| 9 3 6 5|