3x+2y=z=13 x+y+2z=7 2x+2y-z=12三元一次方程组的解

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3x+2y=z=13x+y+2z=72x+2y-z=12三元一次方程组的解3x+2y=z=13x+y+2z=72x+2y-z=12三元一次方程组的解3x+2y=z=13x+y+2z=72x+2y-z=

3x+2y=z=13 x+y+2z=7 2x+2y-z=12三元一次方程组的解
3x+2y=z=13 x+y+2z=7 2x+2y-z=12三元一次方程组的解

3x+2y=z=13 x+y+2z=7 2x+2y-z=12三元一次方程组的解
3x+2y+z=13 ①
x+y+2z=7 ②
2x+2y-z=12 ③
①-3*②得 -y-5z=-8 ④
2*①-3*③得 -2y+5z=-10 ⑤
2*④-⑤得 -15z=-6 z=2/5
代入z到④,得y=6
代入y和z到①,得x=1/5
因此 x=1/5 y=6 z=2/5

3x+2y=z=13 (1)
x+y+2z=7 (2)
2x+2y-z=12 (3)
(1)-2(2)
x-3z=-1
2(2)-(3)
5z=2
z=0.4
x=0.2
y=6

3x+2y+z=13,
x+y+2z=7,2x+2y+4z=14,
2x+2y-z=12,5z=2,z=2/5
3x+2y+z=13,
5x+4y=25,
x+y+4/5=7,5+5y=31,
y=6
x=1/5

3x+2y+z=13 ①
x+y+2z=7 ②
2x+2y-z=12 ③
②式×2-③式，得：5z=2
解得：z=2/5
将z=2/5代入①③式，得：3x+2y=63/5 ④
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3x+2y+z=13 ①
x+y+2z=7 ②
2x+2y-z=12 ③
②式×2-③式，得：5z=2
解得：z=2/5
将z=2/5代入①③式，得：3x+2y=63/5 ④
2x+2y=62/5 ⑤
④式-⑤式，得：x=1/5
将x=1/5，z=2/5，代入②式，得：1/5+y+4/5=7
解得：y=7-4/5-1/5
=6
∴ x=1/5 y=6 z=2/5
（希望你能满意）

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3x+2y+z=13 .............(1)
x+y+2z=7 .................(2)
2x+2y-z=12...............(3)
(1)-(3)式，X+2Z=1....(4)
(2)-(4)式，Y=6代入（1）式，3X+Z=1........(5)
(5)乘以2然后减（4）式，5X=1,将X=0.2代入（4）式中得Z=0.4。
注：你写的时候不要用小数表示，我用电脑不方便写分数，还有我这是用心算的怕有误差，你用笔好好算算。
啦啦啦，望采纳，谢谢亲

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