x+y=4,y+z=3,x+z=-1
(x+y-z)(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+y+z=2 4x+2y+z=4 2x+3y+z=1
X+Y+Z=200,1/3X+4Y+5Z=200,求X,Y,Z等于多少?
x=y/z=z/3,x+y+z =12,求2x+3y+4z是多少,
x-y-z=-1 3x+5y+7z=11 4x-y+2z=-1 分别求出x=?y=?z=?
(x-2y+z)/9=(2x+y+3z)/10=-(3x+2y-4z)/3=1 连等,求x,y,z,
2x+3y+z=1 x+y+z=-2 3x-2y-z=-4 求x、y、z
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.
x,y,z属于正实数,且3x+4y+5z=1 求1/(x+y)+1/(y+z)+1/(x+z)的最小值
X+Y+Z=?
{5x-3y+z=2{5x+2y-4z=3{-5x+y-z=2 {x-y-z=-1{3x+5y+7z{4x-y+2x=-