线性代数的行列式,题目做上三角或下三角,要步骤,谢谢!
1个回答
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A =
2 1 4 1
4 1 2 3
3 4 1 2
2 3 4 1
r2-2r1, r3-r1, r4-r1
A =
2 1 4 1
0 -1 -6 1
1 3 -3 1
0 2 0 0
交换第1,3行
A = -
1 3 -3 1
0 -1 -6 1
2 1 4 1
0 2 0 0
r3-2r1
A = -
1 3 -3 1
0 -1 -6 1
0 -5 10 -1
0 2 0 0
r3-5r2, r4+2r2
A = -
1 3 -3 1
0 -1 -6 1
0 0 40 -6
0 0 -12 2
r3+3r4
A = -
1 3 -3 1
0 -1 -6 1
0 0 4 0
0 0 -12 2
r4+3r3
A = -
1 3 -3 1
0 -1 -6 1
0 0 4 0
0 0 0 2
= 1*1*4*2
= 8
2 1 4 1
4 1 2 3
3 4 1 2
2 3 4 1
r2-2r1, r3-r1, r4-r1
A =
2 1 4 1
0 -1 -6 1
1 3 -3 1
0 2 0 0
交换第1,3行
A = -
1 3 -3 1
0 -1 -6 1
2 1 4 1
0 2 0 0
r3-2r1
A = -
1 3 -3 1
0 -1 -6 1
0 -5 10 -1
0 2 0 0
r3-5r2, r4+2r2
A = -
1 3 -3 1
0 -1 -6 1
0 0 40 -6
0 0 -12 2
r3+3r4
A = -
1 3 -3 1
0 -1 -6 1
0 0 4 0
0 0 -12 2
r4+3r3
A = -
1 3 -3 1
0 -1 -6 1
0 0 4 0
0 0 0 2
= 1*1*4*2
= 8
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