解方程:{2x+3y+z=7,x+y+z=4,3x+y-z=-4{2x+3y+z=7,x+y+z=4,3x+y-z=-4要过程

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解方程:{2x+3y+z=7,x+y+z=4,3x+y-z=-4{2x+3y+z=7,x+y+z=4,3x+y-z=-4要过程
解方程:{2x+3y+z=7,x+y+z=4,3x+y-z=-4
{2x+3y+z=7,x+y+z=4,3x+y-z=-4要过程

解方程:{2x+3y+z=7,x+y+z=4,3x+y-z=-4{2x+3y+z=7,x+y+z=4,3x+y-z=-4要过程
(1)2x+3y+z=7
(2)x+y+z=4
(3)3x+y-z=-4
(1)和(2)相减得(4)x+2y=3
(2)和(3)相加得(5)4x+2y=0
(4)和(5)相减:3x=-3;x=-1代入到(4)
2y=3-x=3-(-1)=4;y=2
z=4-x-y=4-2-(-1)=3