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
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![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](/uploads/image/z/995477-5-7.jpg?t=%E2%91%A0x%2By%2Bz%3D6+3x-y%2B2z%3D12+x-y-3z%3D-4+%E2%91%A1x%2By-z%3D2+4x-2y%2B3y%2B8%3D0+x%2B3y-2z-6%3D0%E2%91%A2x%2F3%3Dy%2F2+y%2F4%3Dz%2F5+x%2By%2Bz%3D60%E4%B8%89%E5%85%83%E4%B8%80%E6%AC%A1%E6%96%B9%E7%A8%8B)
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
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
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
(1)x+y+z=6 ①3x-y+2z=12② x-y-3z=-4 ③
①+②4x+3z=18 ④ ②-③2x+5z=16⑤
⑤×2 4x+10z=32⑥ ⑥-④7z=14 解得z=2 代入⑤2x+5×2=16解得x=3
将x=3 z=2 代入①3+y+2=6解得y=1
x=3 y=1 z=2
(2)x+y-z=2① 4x-2y+3z+8=0 ②x+3y-2z-6=0③
①×4 4x+4y-4z=8④ ④-②6y-7z=16⑤
③-① 2y-z=4 将 z=2y-4代入⑤6y-7(2y-4)=16解得y=1.5 z=2×1.5-4=﹣1
将y=1.5 z=-1代入①x+1.5-(-1)=2解得x=-0.5
x=-0.5 y=1.5 z=-1
(3)x/3=y/2① y/4=z/5② x+y+z=60③
由①得x=3/2y 由②得z=5/4y 代入③3/2y+y+5/4y=60解得y=16
x=3/2×16=24 z=5/4×16=20
x=24 y=16 z=20