名校
解题方法
1 . 零件
分别先在机器
上加工,然后在机器
上加工,加工所需时间(单位:分钟)如表所示.
①若加工顺序为
,则加工完所有零件所需时间最少为________ 分钟;
②改变这5个零件的加工顺序,可以使得加工完所有零件所需时间更少,所需时间最少为________ 分钟,共有_________________ 种排序方法使得所需时间最少.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32d78a86385e8b4b6f4ffff70f7dd2e8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
①若加工顺序为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32d78a86385e8b4b6f4ffff70f7dd2e8.png)
②改变这5个零件的加工顺序,可以使得加工完所有零件所需时间更少,所需时间最少为
机床 零件 | ![]() | ![]() |
![]() | 1 | 5 |
![]() | 8 | 3 |
![]() | 3 | 9 |
![]() | 4 | 5 |
![]() | 7 | 6 |
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名校
解题方法
2 . 定义集合
的“长度”是
,其中a,
R.已如集合
,
,且M,N都是集合
的子集,则集合
的“长度”的最小值是_____ ;若
,集合
的“长度”大于
,则n的取值范围是__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3296f5d3fbd7177849bbd7bd30fbd3a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13502d46b8563c54c09b29b20b3006a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd7701d084d2b153bbea08cfbf63413a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2532b1aa9a6b334d7395fc020bf0a6be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2512da0056b913e36a72419c91a5d8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/640f4732df2e4b84c5e98b47e37d4e65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c81919684bc4047d376c7e57dc6c8f1c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2bc8032a17aee665217899ed88652375.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83ae18508906c21d3e1199f231b1a9a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eac97e6740365c85ad857aff85cefbe5.png)
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3 . 已知抛物线
交x轴于
,
,且
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/24/c9bfb006-0827-4b39-9b0e-0873015fee88.png?resizew=162)
(1)m的值为______ ;
(2)已知点
,
,P,Q均在抛物线上,且
,
时,均有
,则a的取值范围是______ ;
(3)有点
,抛物线交y轴于点C,过B,D作直线
交y轴于E.M为线段
上一点,当
时,则M的横坐标为______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6ec8e5d8786ef56d44bf535551a09f8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe3c48e6f4858150888d0995a0cb8e1a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7b02568a2d65f35225e190b68e8a5ca4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/428c2271836a8e28ccf66dd06738c273.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/24/c9bfb006-0827-4b39-9b0e-0873015fee88.png?resizew=162)
(1)m的值为
(2)已知点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/545046110e0a7d4df4f1cfcdf4fe40ba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53861973282c55a43feb1ab034a55f62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/958d4cb5c007188bda41687ee1286e47.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38d70d194e7bb8b86fc5db975d19192c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1acc35371a619b9ae9beb0de6e966e1.png)
(3)有点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f7c198d5e7103bd6f1f1c9ee02b8b04b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99d76f8f6c9f0432958ff23ea87364c7.png)
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