- #1
aznkid310
- 109
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[SOLVED] 4x4 determinant using upper triangular form
|2 0 1 4|
|3 2 -4 -2|
|2 3 -1 0|
|11 8 -4 6|
Ive done this a number of times and i still can't get the answer. I ended up w/ 275, but the answer is suppose to be zero
1) 2 * |1 0 0.5 2|
|3 2 -4 -2|
|2 3 -1 0|
|11 8 -4 6|
2) 2* |1 0 0.5 2|
|0 2 -5.5 -8|
|0 3 -2 -4|
|0 8 -9.5 -5|
3) (2)(2)*|1 0 0.5 2|
| 0 1 -2.75 -4|
|0 3 -2 -4|
|0 8 -9.5 -5|
4) (2)(2)*|1 0 0.5 2|
| 0 1 -2.75 -4|
|0 0 6.25 8|
|0 0 12.5 27|
5) (2)(2)(6.25)* |1 0 0.5 2|
|0 1 -2.75 -4|
|0 0 1 (32/25)|
|0 0 0 11|
Determinant = 11*2*2*6.25 = 275
Homework Statement
|2 0 1 4|
|3 2 -4 -2|
|2 3 -1 0|
|11 8 -4 6|
Homework Equations
Ive done this a number of times and i still can't get the answer. I ended up w/ 275, but the answer is suppose to be zero
The Attempt at a Solution
1) 2 * |1 0 0.5 2|
|3 2 -4 -2|
|2 3 -1 0|
|11 8 -4 6|
2) 2* |1 0 0.5 2|
|0 2 -5.5 -8|
|0 3 -2 -4|
|0 8 -9.5 -5|
3) (2)(2)*|1 0 0.5 2|
| 0 1 -2.75 -4|
|0 3 -2 -4|
|0 8 -9.5 -5|
4) (2)(2)*|1 0 0.5 2|
| 0 1 -2.75 -4|
|0 0 6.25 8|
|0 0 12.5 27|
5) (2)(2)(6.25)* |1 0 0.5 2|
|0 1 -2.75 -4|
|0 0 1 (32/25)|
|0 0 0 11|
Determinant = 11*2*2*6.25 = 275