已知:x+y+z=0,5x-3y-z=0,求:5x-y+z/2x+8y+7z 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=0求证x*x*x+y*y*y+z*z*z=3xyz 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 已知 (x+y-z)/z=(x-y+z)/y=(y+z-x)/x,且xyz≠0,求代数式 ((x+y)(y+z)(x+z))/xyz 分式加减法：已知x+y/z=x+z/y=y+z/x(x+y+z≠0）,求x+y-z/x+y+z 已知x+y/z=x+z/y=y+z/x(x+y+z≠0）,求x+y-z/x+y+z的步骤 已知x+y/z=x+z/y=y+z/x(x+y+z≠0）,求x+y-z/x+y+z的步骤 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-5y+2z=0 3x-5y-4z=0,求x：y:z 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 已知：4x-5y+2z=0 x+4y-3z=0则：(x*x+y*y+z*z)/(x*y+y*z+z*x)=____. 已知方程组3x+5y+3z=0,3x-5y-8z=0,并且z≠0,求x:z和y:z 已知x-y+z=0,3x+y-5z=0,则x+y+z/x+2y-3z=? 已知x+y-z=0,2x-y+2z=0 求（3x-2y+5z)/(5x-3y+2z)的值 已知:x+y+z=0,5x-3y-z=0,求:5x-y+z/2x+8y+7z 的值 已知3x+4y+5z=0,2x+3y-4z=0,求(x+y+z)/(x-y+z)