Question

线性代数的行列式计算

Answer 1

(1) D =
| 2 -5 1 2|
|-1 2 0 6|
| 1 1 0 3|
|2 -1 0 0|
D =
|-1 2 6|
| 1 1 3|
|2 -1 0|
D =
| 3 2 6|
| 3 1 3|
|0 -1 0|
D =
| 3 6|
| 3 3|
D = 9-18 = -9

(2) D = (1/3)*
| 7 3 2 6|
| 8 -9 4 9|
| 7 -2 7 3|
|15 -9 9 12|
D = (1/3)*
| -7 7 -12 0|
|-13 -3 -17 0|
| 7 -2 7 3|
|-13 -1 -19 0|
D = (-1)*
| -7 7 -12|
|-13 -3 -17|
|-13 -1 -19|
D =
|-98 0 -145|
|26 0 40|
|13 1 19|
D = (-1)*
|-98 -145|
|26 40|
D = 98*40-145*26 = 150