y-2x=-7 5x+3y+2z=2 3x-4z-4=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- 2x+5y+4z=6,3x+y-7z=-4,x+y-z=? 已知2x+5y+4z=6 3x+y-7z=-4求x+y-z 已知方程组4x-5y+2z=0 x+2y=3z 则x:y:z 5x+3y+2z=2011 4x+6y+7z=2012 求x+y+z x-y-z=-1 3x+5y+7z=11 4x-y+2z=-1 分别求出x=?y=?z=? 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.