解方程组1.2x+y+z=7 2.x+2y+z=5 3.x+y+2z=4

解方程组2x+y-z=7 x+y+z =1 2x-y-z=5 解方程组：x+y+z=4,x+y+2z=5,3x+y-z=6 解方程组：2x+3y+4z=20,x+y+z=7 解方程组：x：y：z=4：7：8,x+y+2z=54 解方程组{z=x+y 3x-2y-2z=-5 2x+y-z=3 解方程组 z=x+y 2x-3y+2z=5 x+2y-z=3 解方程组{2x+3y+z=11,x+y+z=0,3x-y+z=-2. x+z=y 7*x=y+z+2 x+y+z=14 解这个方程组、 解方程组x-4y+z=-3,2x+y-z=18,x-y-z=7. 解方程组{3x+y-z=4,2x-y+3z=12,x+y+z=6} x+y/2=z+x/3+y=z/4,...x+y+z=27.解方程组. 已知方程组4x-5y+2z=0 x+2y=3z 则x:y:z