2x+2y+z=0 ,3x+5y+z=0,那么x+2y/x+y+z的值是

已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0 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. 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z、y、z同时满足x+3y-5z=0,2x-y-3z=0,求x:y:z 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 三元一次方程：x+y-z=0 x+2y+z=13 2x-3y+2z=5x+y-z=0 x+2y+z=13 2x-3y+2z=5 2x+z=10 x+y-z=4 3x-y-z=0 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 已知：4x-5y+2z=0 x+4y-3z=0则：(x*x+y*y+z*z)/(x*y+y*z+z*x)=____. 若|x+3|+|y-2|+|2×z+1|=0求(x×z-y×z)(y-x+z)的值 x+y-z=0 x+2y-z=3 2x-3y+2z=5 x+y-z=0 2x-3y+2z=5 x+2y-z=3 已知{x-5y+2z=0 3x-5y-4z=0,求x：y:z x+y+z=0,3x-2y-2z=5,y-z=2x-7 x+y-z=0 x+2y-z= 2x-3y+2z=5 已知x+4y-3z=0,4x-5y+2z=0,则x：y：z 已知方程组4x-5y+2z=0 x+2y=3z 则x:y:z