已知x+2y-z=8,2x-y+z=18 ,求8X+Y-Z的值

已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z 已知：x^2/(z+y)+y^2/(x+z)+z^2/(x+y)=0,求x/(z+y)+y/(x+z)+z/(x+y)的值. 已知X+2Y-Z=8,2X-Y+Z=18,则8X+Y+Z= 已知x+2y-z=8,2x-y+z=18 ,求8X+Y-Z的值 已知(x+y+z)^2=x^2+y^2+z^2,证明x(y+z)+y(z+x)+z(x+y)=0 已知实数x y z满足x/(x+1)=y/(y+2)=z/(z+3)=(x+y+z)/3,求x+y+z的值 已知x、y、z满足方程组：x+y-z=6；y+z-x=2；z+x-y=0 求x、y、z的值 已知X.Y.Z满足方程组,X+y-Z=6y+z-x=2z+x-y=0求X.Y.Z的值 已知实数x y z满足x/(x+1)=y/(y+2)=z/(z+3)=(x+y+z)/3,求x+y+z的值 代数式化简已知z^2=x^2+y^2化简：(x+y+z)(x-y+z)(-x+y+z)(x+y-z) 已知z^2=x^2+y^2,化简(x+y+z)(x-y+z)(-x+y+z)(x+y-z)? 已知x,y,z 大于0,x+y+z=2,求证 xz/y(y+z)+zy/x(x+y)+yx/z(z+x)大于等于2/3 已知关于x y z的方程组2x-3y+5z=7 x+2y-3z=8,则4x+y-z= 已知x,y,z满足2x-y+4z=8,x-2y-z=7,求x-y+z的值.要2种方法 已知X、Y、Z满足2X-Y+4Z=8(1);X-2Y-Z=7(2)求X-Y-Z的值 已知4x-3y+z=0,x+2y-8z=0,xyz不等于0,求x+y-z/x-y+2z的值 已知:X、Y、Z满足2X-Y+4Z=8,X-2Y-Z=7,求X-Y+Z的值