2(x+3y)+(x+y+z)=5.8和3(x+3y)+(x+y+z)=6.3组成方程组,问x+y+z=多少?

2(x+3y)+(x+y+z)=5.8和3(x+3y)+(x+y+z)=6.3组成方程组,问x+y+z=多少? 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 若X:Y:Z=5:6:7那么(Y-X):(Y+Z)和(X+2Y+3Z):(3X+2Y+Z) 已知4X-3Y-3Z=0和X-3Y-Z=0 求3x-2z+y：-x+y+z的值 丨2x-3y+z丨+(x+2y-z)²=0和x+y+z=11组成三元一次方程组,求x,y,z 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0 已知x:y:z=2:3:4求:x+2y/y 和x+2y+3z/3x-2y-z 已知x/3=y/5=z/4,求x+y+z/y和x+y-z/y-x的值,2种方法.急等. x/2=y/3=z/5 x+3y-z/x-3y+z x+2y=3x+2z=4y+z 求x:y:z x+y/2=z+x/3=y+z/4 x+y+z=27 若x+y+z=3y=2z,则x/x+y+z=? 已知方程组2x-3y-4z=0和x+y+z=0,并且z≠0,求x：y与y：z 解x+2y+z=8,2x-y-z=-3,3x+y-2z=-1和x+2y+3z=4,y+z=1,3x+2z=3 已知实数x y z满足x/(x+1)=y/(y+2)=z/(z+3)=(x+y+z)/3,求x+y+z的值 已知实数x y z满足x/(x+1)=y/(y+2)=z/(z+3)=(x+y+z)/3,求x+y+z的值 已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX..