x=2y-9z 2x+4y-6z=4 3x-6y+18z=3

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x=2y-9z 2x+4y-6z=4 3x-6y+18z=3
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x=2y-9z 2x+4y-6z=4 3x-6y+18z=3
x=2y-9z 2x+4y-6z=4 3x-6y+18z=3

x=2y-9z 2x+4y-6z=4 3x-6y+18z=3
此题使用“消元法”
把式一代入式二和式三得：
2（2y-9z）+4y-6z=4
3（2y-9z ）-6y+18z=3
整理得：2y-6z=1
z=-1/3
把z=-1/3代入2y-6z=1,解得y=-1/2
把z=-1/3和y=-1/2代入式一,解得x=2

x=2y-9z ①
2x+4y-6z=4 ②
3x-6y+18z=3 ③
将①代入②中，得
2(2y-9z)+4y-6z=4
4y-18z+4y-6z=4
8y-24z=4 ④
将①代入③中，得
3(2y-9z)-6y+18z=3
6y-27z-6y+18z=3
-9z=3
z=-1/3
将z...

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x=2y-9z ①
2x+4y-6z=4 ②
3x-6y+18z=3 ③
将①代入②中，得
2(2y-9z)+4y-6z=4
4y-18z+4y-6z=4
8y-24z=4 ④
将①代入③中，得
3(2y-9z)-6y+18z=3
6y-27z-6y+18z=3
-9z=3
z=-1/3
将z=-1/3代入④中，得
y=-1/2
∴x=2×(-1/2)-9×(-1/3)=-1-(-3)=2
∴原方程组的解为x=2，y=-1/2，z=-1/3

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