3x-4y-z=0 2x+y-8z=0,求x:y:z把z看成常数,分别用z表示x和y.3x+4y=-5,化为y=kx+b，求k和b

已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 2x+z=10 x+y-z=4 3x-y-z=0 已知4x-3y+z=0,x+2y-8z=0,xyz不等于0,求x+y-z/x-y+2z的值 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0 {2x+y=10 {x-y+z=4 {3x-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 4x+2y+z=3 9x+3y+z=6x+y+z=04x+2y+z=3 9x+3y+z=6 解方程 x+y+z=0 4x+2y+z=3 9x-3y+z=28解方程x+y+z=04x+2y+z=39x-3y+z=28 已知：4x-5y+2z=0 x+4y-3z=0则：(x*x+y*y+z*z)/(x*y+y*z+z*x)=____. 三元一次方程组题目x+y-z=11 y+z-x=5 x-y+z=1x+y=4 y+z=3 x+z=5若已知x-3y+2z=0 2x+3y-8z=0, 且xyz≠0,则x:y:z= x+y+z=4,x-y+z=0,x-z=8怎么解? 已知3x-4y-z=0,2x+y-8z=0,且z≠0,则x：y：z=（ ） 若|x+3|+|y-2|+|2×z+1|=0求(x×z-y×z)(y-x+z)的值 已知x-2y+3z=0,x-3y+4z=0,则x:y:z= 已知2x-y-z=0,3x+4y-2z=0,则x：y：z=? 已知{x-3y+2z=0 3x-3y-4z+0,则x:y:z=?