Determinants

When you see || around a matrix, that means find the determinant

(same things as absolute value)

For a 2x2 matrix:

|a b|

|c d|

To find determinant, ad - bc

For a 3x3, copy the 1st 2 columns of the matrix right next to it and

cross multiply each diagonal, then add and subtract results.

For a 4x4, just use a calculator because it's really complicated.

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Examples:

1. |3 2|

|5 1|

3-10= -7

2. |1 2 4| 1 2

|5 3 1| 5 3

|0 7 2| 0 7

1(3)2 + 2(1)0 + 4(5)7 - 2(5)2 - 1(7)1 - 4(3)0 = 119