![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dbf1c17cfc8419255b5a21c97cdd1514.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e0beb0360cf3ee5ee41d91cc60ffd7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1010846eeec6c9da29640f5aa3f8738.png)
声源 | 与声源的距离 | 声压级 |
燃油汽车 | 10 | |
混合动力汽车 | 10 | |
电动汽车 | 10 | 40 |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/167e6e41ac221847824a72e964f340f1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9bf0198e73b44944ce7a45411899f49.png)
A.![]() | B.![]() |
C.![]() | D.![]() |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c460d6dac73d2ac53d480d124067e79e.png)
A.1.2天 | B.1.8天 |
C.2.5天 | D.3.5天 |
3 . 2019年1月3日嫦娥四号探测器成功实现人类历史上首次月球背面软着陆,我国航天事业取得又一重大成就,实现月球背面软着陆需要解决的一个关键技术问题是地面与探测器的通讯联系.为解决这个问题,发射了嫦娥四号中继星“鹊桥”,鹊桥沿着围绕地月拉格朗日点的轨道运行.
点是平衡点,位于地月连线的延长线上.设地球质量为M1,月球质量为M2,地月距离为R,
点到月球的距离为r,根据牛顿运动定律和万有引力定律,r满足方程:
.
设,由于
的值很小,因此在近似计算中
,则r的近似值为
A.![]() | B.![]() |
C.![]() | D.![]() |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21ed142422c641fb5f033155027a4fe7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27d0ae6b06a4b02496c7ae16251ffed0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c9c651447c78f6511c378a4286fba8d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/25522700e456c259978a6d762e818572.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/35b7cfcc147916ae7eeb5d557fea945e.png)
A.2.57 | B.2.77 | C.2.89 | D.3.26 |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53168695826b0a33a23067b76173c7e5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9b607658935bc6a43c090bf6d1c6867.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a98a72a7efeb821dd42f214cd858eac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/234c3b0ed007cb69c7b6c75fa07e29cd.png)
(1)若一次喷洒4个单位的消毒剂,则有效杀灭时间可达几小时?
(2)若第一次喷洒2个单位的消毒剂,6小时后再喷洒
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d72ce94944e3d4e8a8d5d27cd416b2ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
6 . 某地下车库在排气扇发生故障的情况下测得空气中一氧化碳含量达到了危险状态,经抢修排气扇恢复正常,排气4分钟后测得车库内的一氧化碳浓度为64 ppm,继续排气4分钟后又测得浓度为32 ppm.由检验知该地下车库一氧化碳浓度y(单位:ppm)与排气时间t(单位:分)之间满足函数关系y=f(t),其中(R为常数).若空气中一氧化碳浓度不高于0.5 ppm,人就可以安全进入车库了,则下列说法正确的是( )
A.![]() |
B.![]() |
C.排气12分钟后,人可以安全进入车库 |
D.排气32分钟后,人可以安全进入车库 |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9966dfe9109671c587892bd32f0b6699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c09886ba6ef28531d9a67a3a6b4b3f8.png)
(1)求2023年该款手机的利润
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
(2)当年产量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
①当x=10时,顾客一次购买草莓和西瓜各1盒,需要支付
②在促销活动中,为保证李明每笔订单得到的金额均不低于促销前总价的七折,则x的最大值为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b16138ff034196e330c025fe6747f1a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50cb152ca64ae6f7dddb7093340e5442.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/89e5460e691e60d43c2d63673126ee40.png)
(1)将2020年该产品的利润y万元表示为年促销费用m万元的函数;
(2)该厂家2020年的促销费用投入多少万元时,厂家的利润最大?最大利润是多少?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/17f26cade8fb52ae18a5258ec4e522e4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/89c2223eb86018d2a795a02f6a9889c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b3a84b1415ba4e4ce47676b7a4f4f1d.png)
x | 10 | 20 | 25 | 30 |
110 | 120 | 125 | 120 |
(1)求k的值;
(2)给出两种函数模型:①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a3470b0d4d365e331bf55fbbecbc1bd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09e77750bf1c9fb485ef1372943b2f89.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b3a84b1415ba4e4ce47676b7a4f4f1d.png)
(3)求该商品的日销售收入
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0184fbac1a83242694b5357a1ed0a0c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fb0b0ddc06a9a7daa00c10a567c4d702.png)