①X+Y+Z=111②Y:X=3:2③Y:Z=5:4求x,y,z急～

2y+z=3y ① ,x+3y-z=8,② x+y+2z=13③ 求x,y,z ①X+Y+Z=111②Y:X=3:2③Y:Z=5:4求x,y,z急～ 解三元一次方程组 ①2x-y+z=1 3x+y -2z=2 X+2y-z=3 ②x-4y+z=-3 2x+Y-Z=18 X-Y-Z=7 ③4x+4y+2z=7 6X-4y-z=6 2x-y+z=1 ①x+y+z=6 3x-y+2z=12 x-y-3z=-4 ②x+y-z=2 4x-2y+3y+8=0 x+3y-2z-6=0③x/3=y/2 y/4=z/5 x+y+z=60三元一次方程 已知x/2=y/4=z/7,求①x：y：z.②若2x+y+3z=58,分别求x,y,z的值.③求x+y/x+z的值. 解三元一次方程,①{x+y-z=0{ x+2y+z=13{2x-3y+2z=5②｛x+y-z=11｛y+z-x=5｛z+x-y=1③｛x+y=1｛y+z=6｛z+x=3 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) 解方程组x+y/2=z+x/3=y+z/4①x+y+z=27② 三元一次方程有三题不会帮下忙明天要交了（过程写一下）2x+4y+3z=6 ① x-y-z=2 ① x+y+z=111 ① 3x-2y+5z=11 ② y-z-x=-5 ② y:x=3:2 ② 5x-6y+8z=13 ③ z-x-y=4 ③ y:z=5:4 ③ (:是比值的符号 解方程组x:y=3:2①y:z=5:4②x-y-z=66③ 三元一次方程 X:Y =3:2 ①y:z =5:4 ②x+y+z=66 ③ x:y=3:2①y:z=5:4②x+y+z=66③ ①3x-4y+z=14x+5y+2z=172x+2y-z=3② x:y=3:2y:z=5:4x+y+z=66 解三元一次方程 快①｛2x+y+z=15 ②｛2x+y=3 ③｛x:y=5:3 ④｛x/2=y/3=z/4x+2y+z=16 3x-z=7 x:z=7:2 3x-2y+5z=20x+y+2z=17 x-y+3z=0 x-2y+3z=92 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0 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