ggpp123456
幼苗
共回答了19个问题采纳率:94.7% 举报
(Ⅰ)
![](https://img.yulucn.com/upload/b/d2/bd2970d4410dc01f32805307aa989db6_thumb.jpg)
;(Ⅱ)当
![](https://img.yulucn.com/upload/c/f2/cf2d3bd4ffe3b209ea787f1ef15a4811_thumb.jpg)
时,函数
![](https://img.yulucn.com/upload/4/6e/46eb79172817593588e2ddac827035d9_thumb.jpg)
的递增区间是
![](https://img.yulucn.com/upload/8/83/88356d0dcb4c16ef15162ca9cff23139_thumb.jpg)
;当
![](https://img.yulucn.com/upload/5/ac/5ac6b41bc19d4f8bbaa00eee31d0e11f_thumb.jpg)
时,函数
![](https://img.yulucn.com/upload/4/6e/46eb79172817593588e2ddac827035d9_thumb.jpg)
的递增区间是
![](https://img.yulucn.com/upload/8/83/88356d0dcb4c16ef15162ca9cff23139_thumb.jpg)
,
![](https://img.yulucn.com/upload/6/d7/6d7e690b562a7fb48549b5a356e7c3c0_thumb.jpg)
;当
![](https://img.yulucn.com/upload/c/7e/c7e0a58c59a493890576ee4cab688f4b_thumb.jpg)
时,函数
![](https://img.yulucn.com/upload/4/6e/46eb79172817593588e2ddac827035d9_thumb.jpg)
的递增区间是
![](https://img.yulucn.com/upload/6/b5/6b57fc270fa3a5c555646d73940e7e6b_thumb.jpg)
;当
![](https://img.yulucn.com/upload/7/9d/79d2e4f6dd45352e6360ab272bf4c858_thumb.jpg)
时,函数
![](https://img.yulucn.com/upload/4/6e/46eb79172817593588e2ddac827035d9_thumb.jpg)
的递增区间是
![](https://img.yulucn.com/upload/e/bd/ebd4c9f367029ab41409f6d6f0dbec04_thumb.jpg)
,
![](https://img.yulucn.com/upload/2/be/2be83209376b106e39649c7bee11547b_thumb.jpg)
.
试题分析:(Ⅰ)先求导,由导数的几何意义可得在点
![](https://img.yulucn.com/upload/f/d8/fd803a3da52abeeeec18b0e511d62ce2_thumb.jpg)
的导数即为在此点处切线的斜率。从而可得
![](https://img.yulucn.com/upload/e/e8/ee8ac9e8d166c84a1dd887bf61d7bd01_thumb.jpg)
的值。(Ⅱ)先求导整理可得
![](https://img.yulucn.com/upload/5/4c/54c0e67d760e12fecb8870c384a0a6c0_thumb.jpg)
,当
![](https://img.yulucn.com/upload/c/f2/cf2d3bd4ffe3b209ea787f1ef15a4811_thumb.jpg)
时,
![](https://img.yulucn.com/upload/4/c2/4c24467e5af3bd1c625b066c81880cce_thumb.jpg)
,解导数大于0可得增区间;当
![](https://img.yulucn.com/upload/e/d3/ed30da3666018e707f4983830130c682_thumb.jpg)
时,导数等于0的两根为
![](https://img.yulucn.com/upload/2/c7/2c7b1891a54abba98eefafddcfcb2607_thumb.jpg)
或
![](https://img.yulucn.com/upload/4/47/4478256e211e43f1ef9e67671693285b_thumb.jpg)
,注意对两根大小的讨论,同样解导数大于0可得增区间。
试题解析:(Ⅰ)
![](https://img.yulucn.com/upload/f/73/f7332a7d4c9bd31f9ae9967aa95e107e_thumb.jpg)
=
![](https://img.yulucn.com/upload/d/0b/d0bac768dc74c965fc676856a556005b_thumb.jpg)
(
![](https://img.yulucn.com/upload/0/a7/0a7b4d0489e8bbfc924cb5aad02a58f0_thumb.jpg)
),
![](https://img.yulucn.com/upload/e/a1/ea18407390e4b9116fec35254841df0c_thumb.jpg)
(
![](https://img.yulucn.com/upload/0/a7/0a7b4d0489e8bbfc924cb5aad02a58f0_thumb.jpg)
),
因为曲线
![](https://img.yulucn.com/upload/e/a4/ea4d10a37b43e61b38312a47029d6911_thumb.jpg)
在点
![](https://img.yulucn.com/upload/e/22/e22dafe9f59aaf710cf5be62c6e4c7f2_thumb.jpg)
处的切线与直线
![](https://img.yulucn.com/upload/9/8f/98fba0734f243c4f6a96fd90b63cb530_thumb.jpg)
平行,
![](https://img.yulucn.com/upload/5/54/554ac16e0aa675c15b1a3f69d9590d72_thumb.jpg)
,解得
![](https://img.yulucn.com/upload/b/d2/bd2970d4410dc01f32805307aa989db6_thumb.jpg)
.
(Ⅱ)因为
(1)当
![](https://img.yulucn.com/upload/c/f2/cf2d3bd4ffe3b209ea787f1ef15a4811_thumb.jpg)
时,
![](https://img.yulucn.com/upload/4/c2/4c24467e5af3bd1c625b066c81880cce_thumb.jpg)
.令
![](https://img.yulucn.com/upload/9/9d/99dfeaadd9a0622cce3e0e5624bf3522_thumb.jpg)
解得
(2)
![](https://img.yulucn.com/upload/e/d3/ed30da3666018e707f4983830130c682_thumb.jpg)
时
令
![](https://img.yulucn.com/upload/9/04/904a912f4c6c96303c26f8542cb11897_thumb.jpg)
,解得
![](https://img.yulucn.com/upload/2/c7/2c7b1891a54abba98eefafddcfcb2607_thumb.jpg)
或
![](https://img.yulucn.com/upload/4/47/4478256e211e43f1ef9e67671693285b_thumb.jpg)
.
(ⅰ)当
![](https://img.yulucn.com/upload/e/0f/e0f78bdea9f738a921b3634fb7bcc3dd_thumb.jpg)
即
![](https://img.yulucn.com/upload/5/ac/5ac6b41bc19d4f8bbaa00eee31d0e11f_thumb.jpg)
时,
由
![](https://img.yulucn.com/upload/b/ab/babcb77c2ff81bd5f7ecce8251e588f7_thumb.jpg)
,及
![](https://img.yulucn.com/upload/0/a7/0a7b4d0489e8bbfc924cb5aad02a58f0_thumb.jpg)
得
1年前
7