已知x:2=y:3=z:4,且x+y+z=18,则2x+3y+4z=
已知x:y:z=2:3:4,且x+y+z=18,求x,y,z的值
已知方程组4x-y+3z=0 2x+y+6z=0且xyz不等于0,则x/y+y/z+z/x是多少
已知x:y:z=2:3:4,且x-y+z=36,求x+y+z的值.
已知x+y/2=y+z/3=z+x/4,且x+2y+z=12,求x-2y+z的值
已知x/2=y/3=z/4,且x+y+z不等于0,求2x+3y-4z/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3x-2y-5z=0,2x-5y+4z=0,且x,y,z都不为0,求(3x*x+y*y+4z*z)/(5x*x+y*
已知,x/2=y/3=z/4,则(2x+y-z)/(3x-2y+z)=?
已知{x-3y+2z=0 3x-3y-4z+0,则x:y:z=?
已知2x+5y+4z=15.7x+y+3z=14 则x+y+z=?
已知方程组4x-5y+2z=0 x+2y=3z 则x:y:z
已知x,y,z属于R+(正实数),且xyz(x+y+z)=4+2*根号下3,则(x+y)(y+z)的最小值是?