x+2y-z=0 2x-3z=1 3x-y+2z=4x+2y-z=02x-3z=13x-y+2z=4

若|x+3|+|y-2|+|2×z+1|=0求(x×z-y×z)(y-x+z)的值 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0 试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) 已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z 2x+z=10 x+y-z=4 3x-y-z=0 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-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 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 方程组 (1) x+2y-3z=12 x-3y+2z= - 13 x-y-z=0 (2) x+ y=z 5x-y+z=18 2x+5y+3z= -1 (1)X+Y=15,Y+Z=-6,Z+X=7.(2)X+Y=-14,Y+Z=-7,Z+X=9.(3)X+Y=0,Y+Z=-1,Z+X=-1. 已知xyz≥0,x+y+z=1,化简x（2y-z）/(1+x+3y)+y(2z-x) /(1+y+3z) +z(2x-y)/(1+z+3x) x+y+z=6 x+2y+3z=14 y+1=z 2x-2y+z=0 2x+y-z=1 x+3y-2z=1 x+2y+z=3y+2x-z=0z-2y-3x=-1 x+2y+z=0 x-y+2z=2 2x-y+3z=-1 3X+Y+Z=0,2X-Y+3Z=1,X+2Y-Z=4 {2x-2y+z=0,2x+y-z+1,x+3y-2z=1