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问题: 解线性方程组的问题

3x1+4x2-4x3+2x4=-3
6x1+5x2-2x3+3x4=-1
9x1+3x2+8x3+5x4=9
-3x1-7x2-10x2+x4=2
用消元法解方程组的解.我要详细过程.

解答:

3x1+4x2-4x3+2x4=-3 ⑴
6x1+5x2-2x3+3x4=-1 ⑵
9x1+3x2+8x3+5x4=9 ⑶
-3x1-7x2-10x3+x4=2 ⑷
⑴+⑷
-3x2-14x3+3x4=-1 ⑸
⑴×2-⑵
3x2-6x3+x4=-5 ⑹
⑴×3-⑶
9x2-20x3+x4=-18 ⑺
⑸+ ⑹
-10x3+2x4=-3 ⑻
⑸×3+⑺
-62x3+10x4=-21 ⑼
⑻×5-⑼
12x3=6
x3=1/2
x4=1
x2=-1
x1=1/3