已知x^2+y^2=1,x^2+z^2=2,y^2+z^2=2,求xy+xz+yz的最小值

已知实数x y z满足x/(x+1)=y/(y+2)=z/(z+3)=(x+y+z)/3,求x+y+z的值 已知实数x y z满足x/(x+1)=y/(y+2)=z/(z+3)=(x+y+z)/3,求x+y+z的值 已知：x^2/(z+y)+y^2/(x+z)+z^2/(x+y)=0,求x/(z+y)+y/(x+z)+z/(x+y)的值. 已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z 已知x,y,z>0,xyz(x+y+z)=1,求证（x+y）(x+z)>=2 已知（1）X-Y+Z=0 (2)X+2Y-3Z=0 求X:Y:Z 已知；根号x+根号y-1+根号z-2=1/2(x+y+z),求x、y、z 已知x:y:z=1:3:5,求（2x+3y-z)/(x+y-2z)的值 已知{x：y：z=1：2：3,x+y+z=12,求x、y、z的值 已知｛2x-y-z=0,3x-9y+z=0求1,x:y:z 已知x:y:z=1:2:3,x+y+z=24,求x,y,z 已知X：Y=0.3：1/2,Y：Z=2：3,求X：Y：Z 已知(x+y+z)^2=x^2+y^2+z^2,证明x(y+z)+y(z+x)+z(x+y)=0 代数式化简已知z^2=x^2+y^2化简：(x+y+z)(x-y+z)(-x+y+z)(x+y-z) 已知z^2=x^2+y^2,化简(x+y+z)(x-y+z)(-x+y+z)(x+y-z)? 已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 已知x、y、z满足方程组：x+y-z=6；y+z-x=2；z+x-y=0 求x、y、z的值 已知X.Y.Z满足方程组,X+y-Z=6y+z-x=2z+x-y=0求X.Y.Z的值