已知:3x+4y+5z=12,5x+6y+7z=15.请问:x+2y+3z=?
已知:3x+4y+5z=12,5x+6y+7z=15.请问:x+2y+3z=?
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.
已知x+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z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.
已知3X=4X,5Y=6Z求X+Y:Y+Z
2x+5y+4z=6,3x+y-7z=-4,x+y-z=?
5x+3y+2z=2011 4x+6y+7z=2012 求x+y+z
已知4x-3y-6z=0,x+2y-7z=0,且x,y,z≠0,求2x+3y+6z/x+5y+5z的值.
已知x:y:z=4:5:7,求:(1)2x+3y+z/5z; (2)x+y/y+z.
1.已知x:y:z=4:5:7,求:(一)2x+3y+z/5z; (二)x+y/y+z 非常急,