已知x+y=3,y+z=4,x+z=5,则x+y+z等于( )
已知x+y=3,y+z=4,x+z=5,则x+y+z等于( )
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2x+3y-4z=0,3x+4y+5z=0,求x+y+z/(除以)x-y+z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
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*
1.已知x:y:z=4:5:7,求:(一)2x+3y+z/5z; (二)x+y/y+z 非常急,
X+Y+Z=200,1/3X+4Y+5Z=200,求X,Y,Z等于多少?
(x+y-z)(x-y+z)=
已知3/x+y=4/x+y=5/y+z,求xyz/(x+y)(y+z)(z+x)的值