4x+9y=12 3y-2z-1=0 7x+5z=4又3/4
2x+5y+4z=0,3x+y-7z=0,则x+y-z=?
解方程一;{x+y-z=6,x-3y+2z=1,3x+2y-z=-7.②{3x+4z=7,2x+3y+z=9,5x-9y
x-y-z=-1 3x+5y+7z=11 4x-y+2z=-1 分别求出x=?y=?z=?
已知x+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z的值
{5x-3y+z=2{5x+2y-4z=3{-5x+y-z=2 {x-y-z=-1{3x+5y+7z{4x-y+2x=-
解下列方程组(1)3x-y+z=3 2x+y-3z=11 x+y+z=12(2)5x-4y+4z=13 2x+7y-3z
若x+2y-9z=0,x-2y+5z=0,(x.y.z≠=0)求2x平方+3y平方+7z平方/x平方-4y平方+4z平方
(1)3x+4z=7;2x+3y+z=9;5x-9y+7z=8 (2)3x+4y+z=14;x+5y+2z=17;2x+
若x-2y+4z=1,x+3y-7z=0,则y:z=?
已知x:y:z=4:5:7,求:(1)2x+3y+z/5z; (2)x+y/y+z.
x=y/z=z/3,x+y+z =12,求2x+3y+4z是多少,
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