最纯洁的散养rr
幼苗
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(1)10; (2)销售价格为3.3元/件时,该店每月销售饰品所获得的利润最大.
试题分析:(1)直接代入点(4,21)即可求出
![](https://img.yulucn.com/upload/1/46/1467688b3794793eb84c29c11242074b_thumb.jpg)
;(2)先建立利润函数模型
![](https://img.yulucn.com/upload/5/6f/56f15117547c99cd6321200b5d22532d_thumb.jpg)
,然后由导数确定函数的单调性,求出函数的最值及条件.
试题解析:(1)因为
![](https://img.yulucn.com/upload/d/24/d2405f6ad1ca4fec8bc787480104a1a5_thumb.jpg)
时,
![](https://img.yulucn.com/upload/3/a5/3a5c98d6f965fac3651cf9128dde8a48_thumb.jpg)
,
代入关系式
![](https://img.yulucn.com/upload/c/08/c08909cbf162192feba5173c1fa27a1e_thumb.jpg)
,得
![](https://img.yulucn.com/upload/d/b9/db97abde8949c01fff0b7e5cc364286a_thumb.jpg)
, 2分
解得
![](https://img.yulucn.com/upload/1/46/1467688b3794793eb84c29c11242074b_thumb.jpg)
. 4分
(2)由(1)可知,饰品每月的销售量
![](https://img.yulucn.com/upload/3/7f/37fffc89e8d9458d1048aeb18e18c9f7_thumb.jpg)
,
所以每月销售饰品所获得的利润
![](https://img.yulucn.com/upload/5/6f/56f15117547c99cd6321200b5d22532d_thumb.jpg)
8分
从而
![](https://img.yulucn.com/upload/d/b8/db8f7babfd68902357c6b453a2ff6492_thumb.jpg)
9分
令
![](https://img.yulucn.com/upload/8/ee/8eeffabd628ec9ee4f7030e949df081e_thumb.jpg)
,得
![](https://img.yulucn.com/upload/d/7d/d7db12a7a5af3c2fe6cc901b0e6a2c31_thumb.jpg)
,且在
![](https://img.yulucn.com/upload/2/cd/2cd189352d6dddaa9b5d79166db265de_thumb.jpg)
上,
![](https://img.yulucn.com/upload/e/5d/e5d3eb37c5ad528550741a79ffadc1c2_thumb.jpg)
,函数
![](https://img.yulucn.com/upload/8/76/87654c169f98862bec609a1da7651cc8_thumb.jpg)
单调递增;在
![](https://img.yulucn.com/upload/d/73/d73f7a29b3e86620290059252bb1b00c_thumb.jpg)
上,
![](https://img.yulucn.com/upload/2/6e/26ef29dcfba8eed9f0b293f959ae1423_thumb.jpg)
,函数
![](https://img.yulucn.com/upload/8/76/87654c169f98862bec609a1da7651cc8_thumb.jpg)
单调递减,11分
所以
![](https://img.yulucn.com/upload/d/7d/d7db12a7a5af3c2fe6cc901b0e6a2c31_thumb.jpg)
是函数
![](https://img.yulucn.com/upload/8/76/87654c169f98862bec609a1da7651cc8_thumb.jpg)
在
![](https://img.yulucn.com/upload/5/49/549c0a54ec8ef283560286c67a9c5d83_thumb.jpg)
内的极大值点,也是最大值点,12分
所以当
![](https://img.yulucn.com/upload/f/d7/fd7159f7bef607ecbeeca98cd4c7dbae_thumb.jpg)
时,函数
![](https://img.yulucn.com/upload/8/76/87654c169f98862bec609a1da7651cc8_thumb.jpg)
取得最大值. 即销售价格为3.3元/件时,该店每月销售饰品所获得的利润最大.13分
1年前
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