解方程组{3x+y-z=4,2x-y+3z=12,x+y+z=6}

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解方程组{3x+y-z=4,2x-y+3z=12,x+y+z=6}

解方程组{3x+y-z=4,2x-y+3z=12,x+y+z=6}
解方程组{3x+y-z=4,2x-y+3z=12,x+y+z=6}

解方程组{3x+y-z=4,2x-y+3z=12,x+y+z=6}
{3x+y-z=4①,2x-y+3z=12②,x+y+z=6③}
①+②得5x+2z=16④,②+③得3x+4z=18⑤
④×2—⑤得7x=14,x=2
所以z=3、y=1所以方程组的解为x=2、y=1、z=3

3x+y-z=4(a) 2x-7+3z=12(b) x+y+z=6(c)
a+b得5x+2z=16(1),b+c得3x+4z=18(2)
(1)*2 -(2)得7x=14,即x=2, 将x=2代入(1)得z=3,
将x,z 代入(a),得y=1,
得解 x=2,y=1,z=3

x+4y=6 4x+2y=10