解{x+y=20{y+z=19{x+z=21
(x+y-z)(x-y+z)=
解方程组{x+y=20,y+z=19,x+z=21
解{x+y=20{y+z=19{x+z=21
解三元一次方程组x+y=20,y+z=19,x+z=21
解方程组2X+Y+Z=32,X+2Y+Z=19,X+Y+2Z=21,求X,Y,Z
X+Y+Z=?
解方程组{x(x+y+z)=6,y(x+y+z)=12,z(x+y+z)=18
f(x,y,z,w)=x*(x+y)*(x+y+z)*(x+y+z+w)
x y z x+y--- = --- = ---- ----y+Z z+x x+y ,求 z 的值 .求 x+y----
已知x+y-z/z=x-y+z/y=-x+y+z/x,且xyz不等于0,求分式[(x+y)(x+z)(y+z)]/xyz
若z分之x+y+z=y分之x-y+z=x分之-x+y+z,求xyz分之(x+y)(y+z)(z+x)
y+z÷x=Z+X÷y=X+Y÷z,X+Y+Z不等0求X+Y-Z÷X+Y+z值