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已知x:y:z=3:4:7,且2x-y+z=-18,求x+y+z.
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已知x:y:z=3:4:7,且2x-y+z=-18,求x+y+z.
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答案和解析
∵x:y:z=3:4:7,
∴y=
x,z=
x,
把y=
x,z=
x代入2x-y+z=-18中,得
2x-
x+
x=-18,
解得x=-6,
把x=-6代入y=
x和z=
x中,得
y=-8,z=-14,
∴x+y+z=-6-8-14=-28.
∴y=
4 |
3 |
7 |
3 |
把y=
4 |
3 |
7 |
3 |
2x-
4 |
3 |
7 |
3 |
解得x=-6,
把x=-6代入y=
4 |
3 |
7 |
3 |
y=-8,z=-14,
∴x+y+z=-6-8-14=-28.
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