名校
1 . 根据多元微分求条件极值理论,要求二元函数
在约束条件
的可能极值点,首先构造出一个拉格朗日辅助函数
,其中
为拉格朗日系数.分别对
中的
部分求导,并使之为0,得到三个方程组,如下:
,解此方程组,得出解
,就是二元函数
在约束条件
的可能极值点.
的值代入到
中即为极值.
补充说明:【例】求函数
关于变量
的导数.即:将变量
当做常数,即:
,下标加上
,代表对自变量x进行求导.即拉格朗日乘数法方程组之中的
表示分别对
进行求导.
(1)求函数
关于变量
的导数并求当
处的导数值.
(2)利用拉格朗日乘数法求:设实数
满足
,求
的最大值.
(3)①若
为实数,且
,证明:
.
②设
,求
的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4a1d0dba29a77dd111efcde543d6c1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc4c14935585e8fa61d032730867d771.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67b6f154c6b2de5695eb1807b98c2c63.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/809615d1f91508e2c6c0cda7e592c479.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/244021f826099b18e31af1143597bba2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb5be11a5e6aaf00b2833930b198b4cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0203b006524305c3d8ee0b6c34cd872b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4a1d0dba29a77dd111efcde543d6c1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc4c14935585e8fa61d032730867d771.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b0fffbec1fe851795dfdd448bf0d165.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1c3c1ed4fb65ab9505ad8078d8d0fb5.png)
补充说明:【例】求函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d7ca0caa9933b7afd4bed2683140a07.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aebdee8d81b048b5aa520f7e8ba56ff2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a1e15a54c6122c695239107dd0901bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/244021f826099b18e31af1143597bba2.png)
(1)求函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b3d9ab2fcf15b94f33cb64f84ed906c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b384412acba251d87902ab928902f16.png)
(2)利用拉格朗日乘数法求:设实数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b0fffbec1fe851795dfdd448bf0d165.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c45d8122b61de13875003d00c002c5b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de725a9fc66f67abbe0015131846a648.png)
(3)①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a14c388e1e2e5a2ff1ccf6caffbee0d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd24c686fbaaa68705d654b880481ffe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e778f95c72fec00bfbbc63e6dfd0c460.png)
②设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/497d269c30eec393e3f0e877ddbe2983.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ade042c085bbad8aeaf111b9f4c33408.png)
您最近一年使用:0次
名校
2 . 已知函数
,
.
(1)解方程![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9708c59f51c8ed59a859e288e9ac024.png)
(2)当
时,有
最大值为1,求实数
的值;
(3)若方程
在
上有4个实数解,求实数
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1697647bba92906e733fb696f622a2e2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4139cddc2af2ef0900496dce24274d2.png)
(1)解方程
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9708c59f51c8ed59a859e288e9ac024.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1591d4244dcf5539a4ae98f554e91e61.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4669810732b633b60dbeaf0bf57204f6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
(3)若方程
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f955a011428f5e0d962cd57f8e73b396.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d188ec2580e273ce87e51653a2177ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
您最近一年使用:0次
3 . 已知
,函数
.
(1)当
时,解不等式
;
(2)若关于
的方程
的解集中恰有两个元素,求
的取值范围;
(3)设
,若对任意的
,函数
在区间
上的最大值与最小值的和不大于2,求
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10bbdef421c976962a270a2beabbad91.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c2b2712debcab48c4170c72794d8c471.png)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b108ab31cc093f03cf48ad65429889e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2aeda5c6f101566159dd4c460b943b2.png)
(2)若关于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43e9db9750a44fcef925672cf654dbec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
(3)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94440d3e4c073f94f2b266ff99d50e74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a242d77106235f060b3221b3ea32d486.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c82dca4a0e082b5cbdb1beb6f4d1e2f1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
您最近一年使用:0次
名校
4 . 已知函数
.
(1)当
时,解不等式
;
(2)若关于
的方程
在区间
上恰有一个实数解,求
的取值范围;
(3)设
,若存在
使得函数
在区间
上的最大值和最小值的差不超过1,求
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ab5c53352f3eafd25b5dbf4ee5bbbd6.png)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e65397f11ea8af736f38debadf420c4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/018857ec6e498113b3b12a730d9313da.png)
(2)若关于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f198f304b60422fb5065dcc742ab48a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc6554ac3dff4a59833e407db887f6e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
(3)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94440d3e4c073f94f2b266ff99d50e74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6555c4166361c548b6f4f692d9a66cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c93c82944db4a310a2047dd6d8966162.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
您最近一年使用:0次
2020-02-28更新
|
695次组卷
|
4卷引用:上海市曹杨二中2019-2020学年高一上学期期末数学试题
5 . 已知函数
.
(1)设
是
的反函数.当
时,解不等式
;
(2)若关于
的方程
的解集中恰好有一个元素,求实数
的值;
(3)设
,若对任意
,函数
在区间
上的最大值与最小值的差不超过
,求
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8e4900f308f9aba73d06964d8e61f54.png)
(1)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ab05c7c140f76ce8618a6694b57b30e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d8b6894e8c345a035e89ec672503a01f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b550ee821ee1838384835e81fc34b67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6bd20834857c93040879c02070035b6.png)
(2)若关于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b542881ccda4af9d4cbc1df4ead2638.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
(3)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94440d3e4c073f94f2b266ff99d50e74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb848c2e3353bcb126d14fed803fe2a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d8b6894e8c345a035e89ec672503a01f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aaca9c1dac608a386df1848e8459ce9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e24d42f61784c642e9eb1316afdd2ad.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
您最近一年使用:0次
2020-02-01更新
|
270次组卷
|
2卷引用:上海市杨浦区2018届高三上学期期中数学试题
名校
6 . 已知函数
.
(1)当
时,解不等式
;
(2)若
时,
恒成立,求
的取值范围;
(3)关于
的方程
在区间
内恰有一解,求
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ba3ad818f68e43620ef8abfcf388f55.png)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/302337058242c7b78e3eb4ac7210b7ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f234b18b78bdfbeec2860a3f95a0be84.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0bb71d0371fd8c9ff7d7ae95c4da20fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef854983f312d4765a6fa91bc78974cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
(3)关于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ee07d18565c599ffbdef959e95e9ec68.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d0d025548b510173aeeea5e02d39d0d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
您最近一年使用:0次
2019-11-30更新
|
1044次组卷
|
4卷引用:辽宁省大连市育明高级中学2019-2020学年高一上学期期中数学试题
解题方法
7 . 设函数
.
(1)当
时,解不等式
;
(2)若
,则
在闭区间
上有实数解,求实数
的取值范围;
(3)若函数
的图象过点
,且不等式
对任意
均成立,求实数
的取值集合.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21248b0f3d3ae1495574a88181d20db8.png)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e94f16d5ed858699bfea5039a7bf8ae6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6818d478d5712c1b33034da904d69985.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e61c9a7ed0961f8977a21dab37aab396.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87b28776c37c352e4beb47a11a3420f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9210e75c35fb455d0446eb7ddba7d79c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
(3)若函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/facb8c43b7857be3ceb72cce699e4686.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d19195d1adf801090bcdc5d48b4b8554.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c229aec38946b710076588b7710381c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
您最近一年使用:0次
名校
8 . 已知
,函数
.
(Ⅰ)当
时,解不等式
;
(Ⅱ)若关于
的方程
的解集中恰有一个元素,求
的取值范围;
(Ⅲ)设
,若对任意
,函数
在区间
上的最大值与最小值的和不大于
,求
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44aca6c00903b9dd306287ba3bb91035.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3d79b174269eb75464c8f51ea5bbda0.png)
(Ⅰ)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b550ee821ee1838384835e81fc34b67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98ec7ef12927ef4e2d8f6721a0ae6b15.png)
(Ⅱ)若关于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f19f45b84efe779093d998513130043e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
(Ⅲ)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94440d3e4c073f94f2b266ff99d50e74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64b412654a4e5b9d64e2bfb6f5b12ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d8b6894e8c345a035e89ec672503a01f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97c2e5f67f3eee8766347d429b3de437.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c9bf7f9244224fd181cbc0594de34f8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
您最近一年使用:0次
2018-01-26更新
|
1931次组卷
|
2卷引用:天津市新四区示范校2017-2018学年高一上学期期末联考数学试题
名校
解题方法
9 . 一般地,我们把函数
称为多项式函数,其中系数
,
,…,
.设
,
为两个多项式函数,且对所有的实数
等式
恒成立.
(1)若
,
.
①求
的表达式;
②解不等式
.
(2)若方程
无实数根,证明方程
也无实数解.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5bf5ba3261da10ef4c78b5d611aaf60.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f35f7dcce39f3d4dc6b7faf84dc1d0a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96a5d7258973bf6c6afab73fcc1e8263.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be1ce3f01e2b6364f9a9fdaf197d5e29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34c3e5078eacd04040a3b843f2f8a894.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df4ab5ed446cb4d85ee8f9e93e0985e8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb4935611969e644511329f6b0dbbf3b.png)
①求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be1ce3f01e2b6364f9a9fdaf197d5e29.png)
②解不等式
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca77cbddad9b9b82ee918612de679f27.png)
(2)若方程
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f8bfb563f79688d136e0cb958b5153c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86ed16a1c5b976b543af7d418a9e4905.png)
您最近一年使用:0次
2017-10-31更新
|
454次组卷
|
3卷引用:北京西城35中2016-2017学年高一上学期期中数学试题
10 . 已知
,函数
.
(1)当
时,解不等式
;
(2)若函数
为奇函数,试求
的值;
(3)若关于
的方程
的解集中恰好有一个元素,求
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22dd8b3dc4c609bab82d356a5cc2208d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e02113fb34201302c2c68f71b6efdc3.png)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b550ee821ee1838384835e81fc34b67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c2e0bb6d63b7bcaee92a470d58cc399.png)
(2)若函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0fffac67cbe37813c942198f7ffae609.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
(3)若关于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
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2017-10-11更新
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3卷引用:江苏省镇江市高三10月月考数学文科试题