6x+5y+3z=100 x+y+z=30 求 x y

已知3X=4X,5Y=6Z求X+Y：Y+Z 如果|x+y+z-6|+|2x+3y-z-12|+|2x-y-z|=0求x,y, 5x+3y+2z=2011 4x+6y+7z=2012 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. 已知2x+5y+4z=6 3x+y-7z=-4求x+y-z 若x:y:z=3:4:5=6,求x-y+z分之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. 1.x+y+z=30,3x+y-z=50,x,y,z为非负数,求5x+4y+2z取值范围. x y z x+y--- = --- = ---- ----y+Z z+x x+y ,求 z 的值 .求 x+y---- (x+y-z)(x-y+z)= 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