{2x+y+3z=2}{-2x+3y+2z=-3}{4x+2y+9z=1}解一下吧.谢谢了
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{2x+y+3z=2}{-2x+3y+2z=-3}{4x+2y+9z=1}解一下吧.谢谢了
①2x+y+3z=2
②-2x+3y+2z=-3
③4x+2y+9z=1
用③-2×①,得
4x+2y+9z-2(2x+y+3z)=1-2×2
4x+2y+9z-4x-2y-6z=1-4
3z=-3
z=-1
用①+②,得④
2x+y+3z+(-2x+3y+2z)=2+(-3)
2x+y+3z-2x+3y+2z=2-3
4y+5z=-1
把z=-1代入④,得
4y+5(-1)=-1
4y-5=-1
4y=4
y=1
把y=1、z=-1代入①,得
2x+1+3(-1)=2
2x+1-3=2
2x=4
x=2
x=2、y=1、z=-1
②-2x+3y+2z=-3
③4x+2y+9z=1
用③-2×①,得
4x+2y+9z-2(2x+y+3z)=1-2×2
4x+2y+9z-4x-2y-6z=1-4
3z=-3
z=-1
用①+②,得④
2x+y+3z+(-2x+3y+2z)=2+(-3)
2x+y+3z-2x+3y+2z=2-3
4y+5z=-1
把z=-1代入④,得
4y+5(-1)=-1
4y-5=-1
4y=4
y=1
把y=1、z=-1代入①,得
2x+1+3(-1)=2
2x+1-3=2
2x=4
x=2
x=2、y=1、z=-1
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