3. Example `2x+3y-z=5,3x+2y+z=10,x-5y+3z=0`
Solve Equations 2x+3y-z=5,3x+2y+z=10,x-5y+3z=0 using Inverse Matrix method
Solution: Here `2x+3y-z=5` `3x+2y+z=10` `x-5y+3z=0`
Now converting given equations into matrix form `[[2,3,-1],[3,2,1],[1,-5,3]] [[x],[y],[z]]=[[5],[10],[0]]`
Now, A = `[[2,3,-1],[3,2,1],[1,-5,3]]`, X = `[[x],[y],[z]]` and B = `[[5],[10],[0]]`
`:.AX = B`
`:.X = A^-1 B`
`|A|` | = | | `2` | `3` | `-1` | | | `3` | `2` | `1` | | | `1` | `-5` | `3` | |
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`=2 xx (2 × 3 - 1 × (-5)) -3 xx (3 × 3 - 1 × 1) -1 xx (3 × (-5) - 2 × 1)`
`=2 xx (6 +5) -3 xx (9 -1) -1 xx (-15 -2)`
`=2 xx (11) -3 xx (8) -1 xx (-17)`
`= 22 -24 +17`
`=15`
`"Here, " |A| = 15 != 0`
`:. A^(-1) " is possible."`
`Adj(A)` | = | Adj | | `2` | `3` | `-1` | | | `3` | `2` | `1` | | | `1` | `-5` | `3` | |
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= | | `+(2 × 3 - 1 × (-5))` | `-(3 × 3 - 1 × 1)` | `+(3 × (-5) - 2 × 1)` | | | `-(3 × 3 - (-1) × (-5))` | `+(2 × 3 - (-1) × 1)` | `-(2 × (-5) - 3 × 1)` | | | `+(3 × 1 - (-1) × 2)` | `-(2 × 1 - (-1) × 3)` | `+(2 × 2 - 3 × 3)` | |
| T |
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= | | `+(6 +5)` | `-(9 -1)` | `+(-15 -2)` | | | `-(9 -5)` | `+(6 +1)` | `-(-10 -3)` | | | `+(3 +2)` | `-(2 +3)` | `+(4 -9)` | |
| T |
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= | | `11` | `-8` | `-17` | | | `-4` | `7` | `13` | | | `5` | `-5` | `-5` | |
| T |
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= | | `11` | `-4` | `5` | | | `-8` | `7` | `-5` | | | `-17` | `13` | `-5` | |
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`"Now, "A^(-1)=1/|A| × Adj(A)`
`"Here, "X = A^(-1) × B`
`:. X = 1/|A| × Adj(A) × B`
= | `1/(15)` × | | `11` | `-4` | `5` | | | `-8` | `7` | `-5` | | | `-17` | `13` | `-5` | |
| × | |
= | `1/15` × | | `11×5-4×10+5×0` | | | `-8×5+7×10-5×0` | | | `-17×5+13×10-5×0` | |
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`:.[[x],[y],[z]]=[[1],[2],[3]]`
`:.x=1,y=2,z=3`
This material is intended as a summary. Use your textbook for detail explanation. Any bug, improvement, feedback then
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