已知x:y:z=2:3:4求:x+2y/y 和x+2y+3z/3x-2y-z
已知x/3=y/5=z/4,求x+y+z/y和x+y-z/y-x的值,2种方法.急等.
已知3x=4y,2y=5z,试求x:y:z
已知方程组2x-3y-4z=0和x+y+z=0,并且z≠0,求x:y与y:z
已知x/3=y/4=z/2,求x+2y-z/x+y+z=?
已知x:y:z=3:4:5,3x+2y-4z=18.求:x+y+z.
已知2x=3y=4z求2x-y+z分之x+y+z的值
已知3x-2y-5z=0,2x-5y+4z=0,且x,y,z均不为0,求3x*x+2y*y+5z*z/5x*x+y*y-
已知2x+5y+4z=6 3x+y-7z=-4求x+y-z
已知x:y:z=2:3:4,且x-y+z=36,求x+y+z的值.
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x:y:z=2:3:4,且x+y+z=18,求x,y,z的值