己知x+2y-3z=0,2x+3y+5z=0,求x+y+z/x-y+z的值.

己知x+2y-3z=0,2x+3y+5z=0,求x+y+z/x-y+z的值. 己知x+2y/3=y+3z/4=z+5x/5则x:y:z=__________ 己知3元齐次线性方程组3x+2y-z=0 kx+7y-2z=0 2x-y+3z=0有非零解k 已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0 己知x=2,y+z=1,求代数式x2(-y-z)+4x(z+y)的值. x/2=y/3=z/5 x+3y-z/x-3y+z 已知z、y、z同时满足x+3y-5z=0,2x-y-3z=0,求x:y: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 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 己知x/2=y/3=z/4,求xy+yz+zx/5x的平方+3y的平方+z的平方的值 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 方程组 (1) x+2y-3z=12 x-3y+2z= - 13 x-y-z=0 (2) x+ y=z 5x-y+z=18 2x+5y+3z= -1 已知：4x-5y+2z=0 x+4y-3z=0则：(x*x+y*y+z*z)/(x*y+y*z+z*x)=____. 2x+z=10 x+y-z=4 3x-y-z=0 若|x+3|+|y-2|+|2×z+1|=0求(x×z-y×z)(y-x+z)的值 x+y-z=0 x+2y-z=3 2x-3y+2z=5