1. Example `[[1,2,3],[4,5,6],[7,8,9]]` (Previous example) | 3. Example `[[1,1,1],[-1,-3,-3],[2,4,4]]` (Next example) |
2. Example `[[3,2,4],[2,0,2],[4,2,3]]`
Find determinants using Sarrus Rule ... `[[3,2,4],[2,0,2],[4,2,3]]`Solution:Write first 2 columns of matrix to right of 3rd column, so we have total 5 columns. | `A=` | | 3 | 2 | 4 | 3 | 2 | | | 2 | 0 | 2 | 2 | 0 | | | 4 | 2 | 3 | 4 | 2 | |
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| `A=` | | 3 | 2 | 4 | 3 | 2 | | | 2 | 0 | 2 | 2 | 0 | | | 4 | 2 | 3 | 4 | 2 | |
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Now, add products of diagonals going from top to bottom (blue lines) and subtract products of diagonals going from bottom to top (red lines). `={3*0*3+2*2*4+4*2*2}-{4*0*4+2*2*3+3*2*2}` `=(0+16+16)-(0+12+12)` `=32-24` `=8` Method-2: Determinant by expanding cofactors| `|A|` | = | | `3` | `2` | `4` | | | `2` | `0` | `2` | | | `4` | `2` | `3` | |
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`=3 xx (0 × 3 - 2 × 2) -2 xx (2 × 3 - 2 × 4) +4 xx (2 × 2 - 0 × 4)` `=3 xx (0 -4) -2 xx (6 -8) +4 xx (4 +0)` `=3 xx (-4) -2 xx (-2) +4 xx (4)` `= -12 +4 +16` `=8`
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1. Example `[[1,2,3],[4,5,6],[7,8,9]]` (Previous example) | 3. Example `[[1,1,1],[-1,-3,-3],[2,4,4]]` (Next example) |
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