3x-y+7=0 y+4z-3=0 2x-2z+5=0

2x+5y+4z=0,3x+y-7z=0,则x+y-z=? 已知x+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z的值 若4x-3y-6z=0,x+2y-7z=0,求代数式5x*5x+2y*2y-z*z/2x*2x-3y*3y-10z*10 已知方程组4x-5y+2z=0 x+2y=3z 则x:y:z 已知3x-2y-5z=0,2x-5y+4z=0,且x,y,z均不为0,求3x*x+2y*y+5z*z/5x*x+y*y- 已知{3x+4y+5z=0,2x+3y-4z=0,求x+y+z/x-y+z的值. 已知2x+3y-4z=0,3x+4y+5z=0,求x+y+z/（除以）x-y+z的值. 已知2x+3y-4z=0,3x+4y+5z=0,求x+y+z/x-y+z的值. 已知3x+4y+5z=0,2x+3y-4z=0,求(x+y+z)/(x-y+z) 2x+3y-4z=0,3x+4y+5z=0,求x+y-z/x-y+z的值 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 已知,方程组:4x-3y-7z=0 x+2y=10z 则(x-y+z)÷(x+y+z)=——