.已知 x\2 = y\3 = z\5 ,则分式 2x+3y–z\3x-2y+z =___________

.已知 x\2 = y\3 = z\5 ,则分式 2x+3y–z\3x-2y+z =___________ 已知方程组4x-5y+2z=0 x+2y=3z 则x:y:z 已知2x+5y+4z=15.7x+y+3z=14 则x+y+z=? 试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) x/2=y/3=z/5 x+3y-z/x-3y+z 已知x,y,z 大于0,x+y+z=2,求证 xz/y(y+z)+zy/x(x+y)+yx/z(z+x)大于等于2/3 已知x-y+z=0,3x+y-5z=0,则x+y+z/x+2y-3z=? 已知x-y+z=0.3x+y-5z=0,则x+y+z/x+2y-3z=_______ 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x:y:z=3:4:5,3x+2y-4z=18.求：x+y+z. 已知x/4=y/5=z/6 求x+y+z/3x-2y+z的值