已知x+y/2=y+z/3=z-2x/4=k,且知道x+2y-z=9,求k的值

已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z 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/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 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：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/2=y/3=z/4,则2x+y-z/3x-2y+z=? 已知(x+2y)/2=(y+3z)/3=(z+4x)/4,则x:y:z=? 已知2x-y-z=0,3x+4y-2z=0,则x：y：z=? 已知x/3=y/4=z/2,求x+2y-z/x+y+z=? 已知(x+2y)/3=(y+3z)/4=(z+5x)/5,则x:y:z= 已知x+2y/3=y+3z/4=z+5x/5,则x:y:z=? 已知x+2y/3=y+3z/4=z+5x/5,则x:y:z= 已知x-2y+3z=0,x-3y+4z=0,则x:y:z= 已知{x-3y+2z=0 3x-3y-4z+0,则x:y:z=? 已知方程组4x-5y+2z=0 x+2y=3z 则x:y:z 已知2x+5y+4z=15.7x+y+3z=14 则x+y+z=? 已知2x+5y+4z=6 3x+y-7z=-4求x+y-z