{x+y+z=1 x-2y+3z=5 2x-3y-3z=-8
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{x+y+z=1 x-2y+3z=5 2x-3y-3z=-8
(1)x+y+z=1
(2) x-2y+3z=5
(3) 2x-3y-3z=-8
(2)(3)相加得(4)
(4)3x-5y=-3
(1)式两边×3
3x+3y+3z=3与(3)相加得(5)
2x-3y-3z=-8
(5)5x=-5
x=-1代入到(4)
5y=3*(-1)+3=0
y=0
把x=-1,y=0代入到(1)
z=1-(-1)-0=2
把x=-1,y=0,z=2,带入到原方程
(1)-1+0+2=1(左边)
(2)-1-0+3*2=5(左边)
(3)-2-0-2*3=-8(左边)
三式均与右边相等.
用代入法 X=1-Y-Z带入后面2个
3y+2z=4
5y+5z=10解的x=-1,y=0,z=2可以稍微详细点吗?1-y-z-2y+3z=5 得出1-3y+2z=5, -3y+2z=4(上面这个是错的) 2-2y-2z-3y-3z=-8 得出2-5y-5z=-8 5y+5z=10 把后面2个方程变成 -15y+10z=20 ...
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用代入法 X=1-Y-Z带入后面2个
3y+2z=4
5y+5z=10解的x=-1,y=0,z=2
收起
x+y+z=1 (1)
x-2y+3z=5 (2)
2x-3y-3z=-8 (3)
(1)-(2)得,3y-2z=-4 (4)
(1)乘以2-(3)得,y+z=2(5)
由 (4)(5)得z=2,y=0
带入(1)式得x=-1
收起
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x+y+z=2 x-3y+2z=1 2x+2y+z+5 要具体步骤..