求文档: 若2x+5y+4z=6,3x+y-7y=-5,求x+y+z的值?

求文档: 若2x+5y+4z=6,3x+y-7y=-5,求x+y+z的值? 已知x:：y：z=3：4：5,(1)求x+y分之z的值；（2）若x+y+z=6,求x,y,z. 若x:y:z=3:4:5=6,求x-y+z分之x+y-z的值 若x/3=y/4=z/5,求x+y+z/3x-2y+z的值. 已知2x+5y+4z=6 3x+y-7z=-4求x+y-z 已知x/4=y/5=z/6 求x+y+z/3x-2y+z的值 已知x/4=y/5=z/6,求x+y+z/3x-2y+z的值. 5x+3y+2z=2011 4x+6y+7z=2012 求x+y+z 方程组{x/2+y/3-z=-5,x/3-y/2+z/2=10,x/2-y/3-z/4=6,求x,y,z 已知4x-3y-6z=0,x+2y-7z=0,求5x+2y-z/2x-3y-10z 若xyz≠0且4(x/z)-5(y/z)=-2,(x/z)+4(y/z)=3,求x:y:z 已知3X=4X,5Y=6Z求X+Y：Y+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 若2x+5y+4z=6,3x+y-7z=—4,求x+y+z 若2x+5y+4z=6 3x+y-7z=4 求x+y-z的值 若2x+5y+4z=6,3x+y-7z=—4,求x+y-z补加20分 x+2y=3x+2z=4y+z 求x:y:z 设|x|-|y|+|z|=|x+y+z|,且|x+y|=4,|y+z|=5,|y|=3,求(x-y-z)^2的值