Determinants!

~Notation- | |similar to absolute value

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

~For a 2X2 matrix you use 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:

|2 6|

|1 9|

2(9)-6(1)=12

Ex.2:

find the determinant of:

|5 6 4|

|0 4 7|=-162

|3 8 2|

Ex.3:

find the determinant of:

|1 9 6 4|

|2 5 4 3|=-123

|7 0 8 6|

|5 2 9 8|

Ex.4:

find the determinant of:

|12 3|=174

|2 15|

Ex.5:

find the determinant of:

|2 13 8|

|11 6 3|=-963

|7 5 10|

Ex.6:

find the determinant of:

|0 1 2 3|

|2 0 1 4|=25

|6 2 3 1|

|1 0 0 3|