x+y=3,y+z=4,z+x=5应先求____之值,在运用整体带入法分别求出x=__,y=__,z=__

(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 (4x-2y-z)-{5x-[8y-2z-(x-2y)]-x-(3y-10z)}=? x+y-z=3 y+z-x=5 z+x-y=7 求x,y,z (x+y-z)(x-y+z)= x+y/2=z+x/3=y+z/4 x+y+z=27 x/2=y/3=z/5 x+3y-z/x-3y+z 设|x|-|y|+|z|=|x+y+z|,且|x+y|=4,|y+z|=5,|y|=3,求(x-y-z)^2的值 x+2y=3x+2z=4y+z 求x:y:z (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 已知3X=4X,5Y=6Z求X+Y：Y+Z x,y,z不是0.3z=4y,z=3x求（x+y）：（x+z）. 已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. 一只x/3=y/4=z/5,求x+y+z/x及x+y+z/x-y+z的值 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)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,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) 3x-2y+z=4 x+y-z=5 4x-4y+3z=27