1.{x:y:z=3:4:5 2x+3y-5z=-14
已知2x+5y+4z=15.7x+y+3z=14 则x+y+z=?
x/2=y/3=z/5 x+3y-z/x-3y+z
1.x+y+z=30,3x+y-z=50,x,y,z为非负数,求5x+4y+2z取值范围.
1.已知x:y:z=4:5:7,求:(一)2x+3y+z/5z; (二)x+y/y+z 非常急,
(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai
3x+2y+z=14 ,x+y+z=10,z+2x+3y=1 5
{2x+3y-4z=-5 x+y+z=6 x-y+3z=10
已知x:y:z=3:4:5,3x+2y-4z=18.求:x+y+z.
2x+5y+4z=6,3x+y-7z=-4,x+y-z=?
x/3=y/4=z/5,求x+y+z/3x-2y+z的值,
若x/3=y/4=z/5,求x+y+z/3x-2y+z的值.
2x+5y+4z=0,3x+y-7z=0,则x+y-z=?