x+y+z=30,120x/3=100y/2=200z,怎么得出的解,加解析,求急!

6x+5y+3z=100 x+y+z=30 求 x y X+Y+Z=30 120X:100Y:200Z=3:2:1 x+y+z=30 120x=600z 100y=400z x+y+z=30 x+y+z=30 120x=3*200z 100y=2*200z 这个方程怎么解三元一次方程 x+y+z=30 解方程：120x=3*200z 100y=2*200z (x+y-z)(x-y+z)= 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) x+y-z=3 y+z-x=5 z+x-y=7 求x,y,z X+Y+Z=? 已知x+y+z=0求证x*x*x+y*y*y+z*z*z=3xyz 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0 x/y=(x+z)/(y+z)y/z=(x+y)/(x+z) 10X+Y+1/3Z=10Y+X 10X+Y+2/3Z=100X+Y 14x+4y+z=200,x+y+z=100求解x,y,z 已知 x/(y+z)+y/(z+x)+z/(x+y)=1求 (x*x)/(y+z)+(y*y)/(x+z)+(z*z)/(x+y)=? x/2=y/3=z/5 x+3y-z/x-3y+z x+y/2=z+x/3=y+z/4 x+y+z=27