已知3x+7y+4z=35,x+5y+2z=40,则x+y+z=______.
已知3x+7y+4z=35,x+5y+2z=40,则x+y+z=______.
已知2x+5y+4z=15,7x+y+3z=14,则4x+y+2z的值为______.
已知2x+5y+4z=15.7x+y+3z=14 则x+y+z=?
已知2x+5y+4z=6 3x+y-7z=-4求x+y-z
已知方程组4x-5y+2z=0 x+2y=3z 则x:y:z
已知,方程组:4x-3y-7z=0 x+2y=10z 则(x-y+z)÷(x+y+z)=——
已知x+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z的值
已知实数z、y、z满足x+y=5及z2=xy+y-9,则x+2y+3z=______.
已知2x-y-z=0,3x+4y-2z=0,则x:y:z=______.
已知2x+3y-4z=7 3x-2y+z=3 x+5y+9z=20 则 x+y+z= 若x :y :z=2 :3 :7
2x+5y+4z=0,3x+y-7z=0,则x+y-z=?
已知x:y:z=4:5:7,求:(1)2x+3y+z/5z; (2)x+y/y+z.