数学
{3x-y+2z=11 2x+y-4z=-12 7x-2y-6z=-7这个三元一次方程怎么解,过程要详略得当

2019-05-27

{3x-y+2z=11 2x+y-4z=-12 7x-2y-6z=-7这个三元一次方程怎么解,过程要详略得当
优质解答
3x-y+2z=11 (1)
2x+y-4z=-12 (2)
7x-2y-6z=-7 (3)
(1)+(2)得
5x-2z=-1 (4)
(2)*2+(3)得
11x-14z=-31 (5)
(4)*7-(5)
9x=24
x=7/3
代入(4)
35/3-2z=-1
2z=32/3
z=16/3
代入(1)得
7-y+32/3=11
y=32/3-4=20/3
3x-y+2z=11 (1)
2x+y-4z=-12 (2)
7x-2y-6z=-7 (3)
(1)+(2)得
5x-2z=-1 (4)
(2)*2+(3)得
11x-14z=-31 (5)
(4)*7-(5)
9x=24
x=7/3
代入(4)
35/3-2z=-1
2z=32/3
z=16/3
代入(1)得
7-y+32/3=11
y=32/3-4=20/3
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