若x-4y+5z=2,5x+4y+z=4,则x+y=

若x/2=y/3=z/4,则3x-2y+5z/x+y+z= 若4x=7y+5z,2x+y=z,则x:y:z的值为 若x/3=y/4=z/5,求x+y+z/3x-2y+z的值. 若xyz≠0且4(x/z)-5(y/z)=-2,(x/z)+4(y/z)=3,求x:y:z (4x-2y-z)-{5x-[8y-2z-(x-2y)]-x-(3y-10z)}=? 已知x:：y：z=3：4：5,(1)求x+y分之z的值；（2）若x+y+z=6,求x,y,z. 若x,y,z成等差数列,则(z-x)^2-4(x-y)(y-z)= 设|x|-|y|+|z|=|x+y+z|,且|x+y|=4,|y+z|=5,|y|=3,求(x-y-z)^2的值 (4x-2y-z)-{5x-[8y-2z-(x+y)]-2(3y-10z)}=?好难啊 x+y=5 2x+3y-z=9 x-y+z=4 {x+y+z=12 x+2y+5z=22 x=4y (x+y):(y+z):(z+x)=3:4:5 3x+y-z=-4已知(x+y):(y+z):(z+x)=3:4:5 ；3x+y-z=-4求x y z 已知XY=2(X+Y),YZ=4(Y+Z),ZX=5(Z+X),求X,Y,Z已知XY=2(X+Y),YZ=4(Y+Z),ZX=5(Z+X),求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)=____. 1.若3x-2y+z=2;3x+2y+5z=4,求x+22.若x-3y+z=0;3x-3y-4z=0,求x:y:z x+y+z=4,x+2y-z=4,3x-y+4z=5 3x-2y+z=4 x+y-z=5 4x-4y+3z=27 2x+5y+4z=6,3x+y-7z=-4,x+y-z=?