1. Find `A^-1` ...
`A=[[1,2],[4,5]]`
Solution:
`=1 × 5 - 2 × 4`
`=5 -8`
`=-3`
`"Now, "A^(-1)=1/|A| × Adj(A)`
= | | `-1.6667` | `0.6667` | | | `1.3333` | `-0.3333` | |
|
2. Find `A^-1` ...
`A=[[1,2,3],[4,5,6],[7,8,9]]`
Solution:
`|A|` | = | | `1` | `2` | `3` | | | `4` | `5` | `6` | | | `7` | `8` | `9` | |
|
`=1 xx (5 × 9 - 6 × 8) -2 xx (4 × 9 - 6 × 7) +3 xx (4 × 8 - 5 × 7)`
`=1 xx (45 -48) -2 xx (36 -42) +3 xx (32 -35)`
`=1 xx (-3) -2 xx (-6) +3 xx (-3)`
`= -3 +12 -9`
`=0`
`Here, |A|=0, " So " (A)^(-1)" is not possible."`
This material is intended as a summary. Use your textbook for detail explanation.
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