计算:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfeb7eca42d17908b8a0b9b62506183b.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfeb7eca42d17908b8a0b9b62506183b.png)
更新时间:2018-12-10 07:48:08
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【知识点】 对数的运算
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填空题-单空题
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【推荐1】以下结论中,正确结论的序号是__________ .
①
;
②
;
③若
,则
;
④若
,则
;
⑤若
,则
.
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d4aa4684bbbdbc05b4f0991a4dd4962.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2bfcf35cfca1e0b5af2897b6f26b88be.png)
③若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38b5902741445e585e8e6f15307c2dee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22ff06692c025b869a7bcdcff15dca9e.png)
④若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30bf3663125e0f3f34f42df7502e43ed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba53065eb180a682305fddb95d14b62f.png)
⑤若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbebbff155a19f69bb3927f7885ee87a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294250dbd576bff3da0a1456cb9a88a5.png)
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【推荐2】中国茶文化博大精深.小明在茶艺选修课中了解到,不同类型的茶叶由于在水中溶解性的差别,达到最佳口感的水温不同.为了方便控制水温,小明联想到牛顿提出的物体在常温环境下温度变化的冷却模型:如果物体的初始温度是
,环境温度是
,则经过时间
(单位:分)后物体温度
将满足:
,其中
为正的常数.小明与同学一起通过多次测量求平均值的方法得到
初始温度为
的水在
室温中温度下降到相应温度所需时间如表所示:
(1)
的值约为___________ ;(填序号)
①0.04;②0.05;③;0.06④0.07.
(2)“碧螺春”用
左右的水冲泡可使茶汤清澈明亮,口感最佳.在(1)的条件下,
水煮沸后在
室温下为获得最佳口感大约冷却___________ .(精确到个位)分钟左右冲泡.
(参考数据:
,
,
,
,
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/25f64fa38725c136504f723019a18dc5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a4438bae1705c0f26beddf41322c087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b4136fb930bcd68e91dc3d685d3e286.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75355b802e13490c8592a2e59fff9188.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/52c1c80864a01904f84b2c611f8fe8b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cac7ac0881afb8803a304d1589e19cb9.png)
从![]() ![]() | 1分58秒 |
从![]() ![]() | 3分24秒 |
从![]() ![]() | 4分57秒 |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
①0.04;②0.05;③;0.06④0.07.
(2)“碧螺春”用
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92cef34e4b823bd59ed57a89ce93991a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55ab9dda2f0cfa9c22ae0a8e3dc3d80e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cac7ac0881afb8803a304d1589e19cb9.png)
(参考数据:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e56c295ab6045e8e0cb85d80585412a0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ab604d33f8b01e4257da2749e2d428d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c2b6864a56a55f5263204fe3dbca5216.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9112e6da071b4d6d8ce62d37340137d3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e9d4ea3601506dbbcaecfd44e490f40.png)
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