若2x+5y+4z=0,3x+y+7z=0,则x+y-z=?A 0B 1C 2D 不能求出说出怎么想的即可!

X-Y-Z=0 X+Y-3Z=4 2X-5Y+7Z=21 若xyz≠0且4(x/z)-5(y/z)=-2,(x/z)+4(y/z)=3,求x:y:z 1.{x:y:z=3:4:5 2x+3y-5z=-142.{x-y-z=-1 3x+5y+7z=11 4x-y+2z=-13.{x+y=1 x+z=0 2x+y+2z=44.{x-y+z=-3 2x-y-z=-2 -3x+y+z=-15.{x-y+z=-3 3x+y-4z=6 2x+y-z=36.{x-2y+5z=16 2x+y-5z=7 2x-y+z=38 若4x-3y-6z=0,x+2y-7z=0,则x+y+z/3x-y+z=? 已知4x-3y-6z=0,x+2y-7z=0,求5x+2y-z/2x-3y-10z 已知x+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z的值 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 三元一次方程解 1.{x+y-z=5 {3x+2y+z=2 {2x-2y+z=-31.{x+y-z=5 2.{9x-5y+x=-6 3.{x-y=3 4.{x+y=3 5.{4x-2y+z=7{3x+2y+z=2 {9x+y-2z=3 {x+z=7 {y+z=4 {2x-y-3z=28{2x-2y+z=-3 {-9x+3y-5z=0 {y-z=6 {z+x=5 {x+y-2z=13 已知x,y,z满足方程组x-2y+z=0 7x+4y-5z=0,且z不等于0,2x²-3y²+z²/y²-2z²的值为? 已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 若X:Y:Z=5:6:7那么(Y-X):(Y+Z)和(X+2Y+3Z):(3X+2Y+Z) 1.若3x-2y+z=2;3x+2y+5z=4,求x+22.若x-3y+z=0;3x-3y-4z=0,求x:y:z 六年级三元一次方程组.解下列方程组：(1)5x-3y+z=25x+2y-4z=3-5x+y-z=2(2)x-y-z=-13x_5y+7z=114x-y+2z=-1(3)9x-5y+z=-69x+y+4z=3-9x+3y-5z=0(4)x+y=22x+z=-27y+z=13 已知：4x-5y+2z=0 x+4y-3z=0则：(x*x+y*y+z*z)/(x*y+y*z+z*x)=____. 三元一次方程组题目x+y-z=11 y+z-x=5 x-y+z=1x+y=4 y+z=3 x+z=5若已知x-3y+2z=0 2x+3y-8z=0, 且xyz≠0,则x:y:z= 2x+z=10 x+y-z=4 3x-y-z=0 若z≠0,且4x=7y+5z,2x+y=z,求x,y,z的值 若|x+3|+|y-2|+|2×z+1|=0求(x×z-y×z)(y-x+z)的值