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Unit 4: Determinants
Notes
2 2
4202 4203
C 1 C 2
0 2
1 4203
Expand
0(4203) ( 1)( 2)
2
12 0 0
5. Let 4 3 0
2 2 3
Expand
12( 9 0) 0( 12 0) 0(8 6)
108 0 0 108
4.8 Examples on Adjoint and Inverse
Example: Find the adjoint of the following matrices
2 1 1 5 3 0
1. 2. 3.
4 7 2 8 5 9
2 1 5 1 5 6 9 1 2
4 0 1 0 7 11 0 8 1
4. 5. 6.
9 3 6 5 2 4 5 1 7
2 7 3
4 10 1
7.
3 5 8
Solution:
2 1
1. A
4 7
Cofactor of 2 = + (7) = 7
Cofactor of 1 = (4) = 4 I column
Cofactor of 4 = ( 1) = 1
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