解方程组:3x-y+2x=20 2x+y-4z=40 7x+y+5z=55

解方程组：2x+3y+4z=20,x+y+z=7 解方程组：x+y+z=4,x+y+2z=5,3x+y-z=6 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+y-z=7 x+y+z =1 2x-y-z=5 解方程组{3x+y-z=4,2x-y+3z=12,x+y+z=6} 解方程组x-4y+z=-3,2x+y-z=18,x-y-z=7. 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 已知,方程组:4x-3y-7z=0 x+2y=10z 则(x-y+z)÷(x+y+z)=—— 4x-3y-6z=0,x+2y-7z=0是一个方程组,那么x-y+z/x+y+z的值等于 三元一次方程组2x+z=3 3x+y-z=8 x+3y+2z=3 5x+2y-3z=2 x+2y+z=6 7x-2y-4