若x+2y-9z=0,z-3y-5z=0,（xyz≠0）求：x²-4y²+9z²分之（2x²+3y²+7z²）若x+2y-9z=0,z-3y-5z=0,（xyz≠0）,求：（x²-4y²+9z²）分之（2x²+3y²+7z²）的值.

已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 若xyz≠0且4(x/z)-5(y/z)=-2,(x/z)+4(y/z)=3,求x:y:z 若|x+3|+|y-2|+|2×z+1|=0求(x×z-y×z)(y-x+z)的值 2x+3y-z=9,x+y+z=15,5x-4y-z=0 9x-5y+z=-6 9x+y-2z=3 -9x+3y-5z=0 求x y z 若x+2y-9z=0,x-2y+5z=0,(x.y.z≠=0)求2x平方+3y平方+7z平方/x平方-4y平方+4z平方 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0 已知z、y、z同时满足x+3y-5z=0,2x-y-3z=0,求x:y:z 三元一次方程解 1.{x+y-z=5 {3x+2y+z=2 {2x-2y+z=-31.{x+y-z=5 2.{9x-5y+x=-6 3.{x-y=3 4.{x+y=3 5.{4x-2y+z=7{3x+2y+z=2 {9x+y-2z=3 {x+z=7 {y+z=4 {2x-y-3z=28{2x-2y+z=-3 {-9x+3y-5z=0 {y-z=6 {z+x=5 {x+y-2z=13 x+5y-3z=0 y+4z=9 2x-z=0 三元一次求解、急!x+5y-3z=0y+4z=92x-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 数学题在线解答：三元一次方程组；(1)X+Y+Z=0,4X+2Y+Z=0,Z=2;(2)9X+3Y+Z=0,X-Y+Z=0,Z=-3,(3)4X+2Y+Z=5,4X-2Y+Z=1Z=-1;(5)5X+2Y+Z=12,4X+3Y+Z=13,Z=3 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 六年级三元一次方程组.解下列方程组：(1)5x-3y+z=25x+2y-4z=3-5x+y-z=2(2)x-y-z=-13x_5y+7z=114x-y+2z=-1(3)9x-5y+z=-69x+y+4z=3-9x+3y-5z=0(4)x+y=22x+z=-27y+z=13 若x+2y-9z=0,z-3y-5z=0,（xyz≠0）求：x²-4y²+9z²分之（2x²+3y²+7z²）若x+2y-9z=0,z-3y-5z=0,（xyz≠0）,求：（x²-4y²+9z²）分之（2x²+3y²+7z²）的值. 2x+z=10 x+y-z=4 3x-y-z=0 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