三元一次方程组,1.x-2y+z=9 2x+y+3z=10 3x+2y1.x-2y+z=92x+y+3z=103x+2y-z2.3x-5y+2z=14x+5y-z=5X-5y+3z=-23.7x+2y-z=76x-y+z=74x+3y+z=94.4x+3y-2z=-75x-6y+z=12x+z=-25.2x+3y-4z=-23x-2y+5z=262x+5z=31

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三元一次方程组,1.x-2y+z=9 2x+y+3z=10 3x+2y1.x-2y+z=92x+y+3z=103x+2y-z2.3x-5y+2z=14x+5y-z=5X-5y+3z=-23.7x+2y-z=76x-y+z=74x+3y+z=94.4x+3y-2z=-75x-6y+z=12x+z=-25.2x+3y-4z=-23x-2y+5z=262x+5z=31

三元一次方程组,1.x-2y+z=9 2x+y+3z=10 3x+2y1.x-2y+z=92x+y+3z=103x+2y-z2.3x-5y+2z=14x+5y-z=5X-5y+3z=-23.7x+2y-z=76x-y+z=74x+3y+z=94.4x+3y-2z=-75x-6y+z=12x+z=-25.2x+3y-4z=-23x-2y+5z=262x+5z=31
三元一次方程组,1.x-2y+z=9 2x+y+3z=10 3x+2y
1.x-2y+z=9
2x+y+3z=10
3x+2y-z
2.3x-5y+2z=1
4x+5y-z=5
X-5y+3z=-2
3.7x+2y-z=7
6x-y+z=7
4x+3y+z=9
4.4x+3y-2z=-7
5x-6y+z=1
2x+z=-2
5.2x+3y-4z=-2
3x-2y+5z=26
2x+5z=31

三元一次方程组,1.x-2y+z=9 2x+y+3z=10 3x+2y1.x-2y+z=92x+y+3z=103x+2y-z2.3x-5y+2z=14x+5y-z=5X-5y+3z=-23.7x+2y-z=76x-y+z=74x+3y+z=94.4x+3y-2z=-75x-6y+z=12x+z=-25.2x+3y-4z=-23x-2y+5z=262x+5z=31
由1式得z=9-x+2y
带入2中得2x+y+27-3x+6y-10=0
      得x-7y-17=0
        x=7y+17
把z=9-x+2y带入3中得
3x+2y-36+4x-8y+3=0
7x-6y-33=0
把x=7y+17带入
7x-6y-33=0
得49y+119-6y-33=0
得y=-2带入 x=7y+17
得x=3
把y=2 x=31带入1式中
得z=2
所以x=3 y=-2 z=2
3x-5y+2z=1  (1)
4x+5y-z=5    (2)
x-5y+3z=-2  (3)
(1)+(2)得7x+z=6  (4)
(2)+(3)得5x+2z=3 (5)
(4)X2-(5)得9x=9 .所以x=1
将x=1代入(4)得z=-1
将x=1、z=-1代入(1)得y=0
即此题结果:x=1、y=0、z=-1
7x+2y-z=7 ①
6x-y+z=7  ②
4x+3y+z=9 ③
由①+②可得13x+y=14  ==>65x+5y=70 ④
由①+③可得11x+5y=16  ⑤

由④-⑤可得54x=54 ==>x=1
代入⑤可得11+5y=16 ==>y=1

再代入①可得7+2-z=7 ==>z=
所以x=y=1  z=2
(1)×2+(2)得
13x-3z=-13     (4)
(3)×3+(4)得
19x=-19
∴x=-1
把x=-1代入(3)得
-2+z=-2
∴z=0
把x=1,z=0代入(2)得
-5-6y=1
y=-1
∴方程组的解是
x=-1
y=-1
z=0

x+3y-4z=-2(1)
3x-2y+5z=26 (2)
2x+5z=31(3)
(1)x5+(2)x4得
22X+7Y=94    (4)
(2)-(3)得
X-2Y=-5,变形得X=2Y-5  (5)
把(5)代入(4)得出Y=4,再代入(5)得X=3,再求出Z=5,
所以X=3
Y=4
Z=5