2x=5y,2z=3y,3x=多少z

x/2=y/3=z/5 x+3y-z/x-3y+z 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 已知x,y,z,满足2/x=3/(y-z)=5/(z+x),则(5x-y)/(y+2z)的值为多少? 已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 如果x=3y,z=x/2,那么(x-y+z)/(x+y+z)=多少? 2x=5y,2z=3y,3x=多少z 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0 (4x-2y-z)-{5x-[8y-2z-(x-2y)]-x-(3y-10z)}=? x+y/2=z+x/3=y+z/4 x+y+z=27 若x+y+z=3y=2z,则x/x+y+z=? x+2y=3x+2z=4y+z 求x:y:z {x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 200分求数学题,急x+y-z=-14x-3y+2z=162x-2y-3z=5求z等于多少 x+2y+3z=23 y-z=5 x+2z=10 设|x|-|y|+|z|=|x+y+z|,且|x+y|=4,|y+z|=5,|y|=3,求(x-y-z)^2的值 thank you已知x+3y+5z=0,2x+3y+z=0 且x、y、z.都不是0,则（2y-z）（2y+z）除以z的平方等多少? 4x+9y=12 3y-2y+5z=11 5x-6y+7z=13 求：x y z等于多少