已知x+3y+5z=0,2x+3y+z=0且x,y,z都不是零,则（2y-x)(2y+x)除以Z^2=()

已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 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)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,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-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x+y-z=0,2x-y+2z=0 求（3x-2y+5z)/(5x-3y+2z)的值 已知x-y+z=0,3x+y-5z=0,则x+y+z/x+2y-3z=? 已知4x-3y-6z=0,x+2y-7z=0,求5x+2y-z/2x-3y-10z 已知x+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z的值 已知x+2y-3z=0,2x+3y+5z=0,求(x+y+z)除以（x-y+z) 已知x+2y-3z=0,2x+3y+5z=0,求(x+y+z)除以（x-y+z) 已知3x+4y+5z=0,2x+3y-4z=0,求(x+y+z)/(x-y+z) 已知2x+3y-4z=0,3x+4y+5z=0,求x+y+z/（除以）x-y+z的值. 已知{3x+4y+5z=0,2x+3y-4z=0,求x+y+z/x-y+z的值. 已知x,y,z,同时满足方程x+3y-5z=0,2x-y-3z=0求x：y：z的值