解三元一次方程组 2x=3y① 4y=5z② x+y+z=66③ 第二道 3x-y+z=4① 2x+3y-z=12② x+y+z=6 帮我解
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![解三元一次方程组 2x=3y① 4y=5z② x+y+z=66③ 第二道 3x-y+z=4① 2x+3y-z=12② x+y+z=6 帮我解](/uploads/image/z/226328-32-8.jpg?t=%E8%A7%A3%E4%B8%89%E5%85%83%E4%B8%80%E6%AC%A1%E6%96%B9%E7%A8%8B%E7%BB%84+2x%3D3y%E2%91%A0+4y%3D5z%E2%91%A1+x%2By%2Bz%3D66%E2%91%A2+%E7%AC%AC%E4%BA%8C%E9%81%93+3x-y%2Bz%3D4%E2%91%A0+2x%2B3y-z%3D12%E2%91%A1+x%2By%2Bz%3D6+%E5%B8%AE%E6%88%91%E8%A7%A3)
解三元一次方程组 2x=3y① 4y=5z② x+y+z=66③ 第二道 3x-y+z=4① 2x+3y-z=12② x+y+z=6 帮我解
解三元一次方程组 2x=3y① 4y=5z② x+y+z=66③ 第二道 3x-y+z=4① 2x+3y-z=12② x+y+z=6 帮我解
解三元一次方程组 2x=3y① 4y=5z② x+y+z=66③ 第二道 3x-y+z=4① 2x+3y-z=12② x+y+z=6 帮我解
由①,得y=(2/3)x ,④
将④代入②,得 (8/3)x=5z ,即z=(8/15)x ,⑤
将④,⑤代入 ③,得(1+2/3+8/15)x=66
(11/5)x=66
解得x=30 y=20 z=16
①+②,得 5x+2y=16 ④
②+③,得 3x+4y=18 ⑤,
④-⑤,解得 x=2
将x=2 代入④,得y=3
将x=2 ,y=3代入x+y+z=6,得z=1
第一道:
x=3/2y,z=4/5y,代入③,得
y=20,x=30,z=16
第二道:
x=2,y=3,z=1
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