名校
解题方法
1 . 已知函数
,
(
).
(1)当
时,解关于x的不等式
;
(2)判断函数
的奇偶性,并证明;
(3)若
在
上恒成立,求a的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6987701d00f14d9c9cd45cbdb000607b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/597ca5bf7e8d0959c1ca65962b6a4200.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5f7f23e7f20dd8bc65a4967cd306782.png)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b550ee821ee1838384835e81fc34b67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22e38c541dec8fce1d26886e5ef7d21f.png)
(2)判断函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df49341b57eb107f416a014903ce25a8.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5ed9438ae4a904513246620ab76403d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/870ebc2f7aabb028024894568d749934.png)
您最近一年使用:0次
解题方法
2 . 已知
,求证
.某同学解这道题时,注意到结论中的三个量
,
,
.由已知条件得到
,
,
.进一步发现三者的关系:
.又观察左边式子的结构发现就是两个数的倒数和,从而联想到以前做过的题目“已知
,
,求证
”,类比其解法得到题目的解法:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f60d4d44e161c4c3e151ad73024a8228.png)
,当且仅当
时取等号.所以
.求
的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/497d269c30eec393e3f0e877ddbe2983.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/323f4e181b418a66cc36d75e0f8da126.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c9f2416d1f75a45a314331146550832e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9db8d3facff8f90f28a936fc5b3ab878.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ea712984ea5017140e20bee226fd5af.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/481ee0d1e39e92a4732eea90225eb94c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/936553b69099e03189581a42a5c1d8aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6e90787c63ca5b5f1a45e0f6e85aaa1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0c05be59bdd7874fd8e9ee5ba5b17f4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94440d3e4c073f94f2b266ff99d50e74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67ca5fd57c2c2fcc3c7a574fdd1467d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86546d8c56d9c72822cc2c834e240ad1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f60d4d44e161c4c3e151ad73024a8228.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55eb4703dc394b53fef7d12030c470d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/914c9d4dc14490413e77f6262d2a7aa9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/323f4e181b418a66cc36d75e0f8da126.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81e743594b98ac2006344494dddfb345.png)
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解题方法
3 . 甲、乙同学分别解“已知
,若
,求
的最小值”的过程如下:
甲:由基本不等式得
,因为
,故有
,即有
,又
,故
;
乙:因为
,有
,
.
同学们,请通过思考用合适的方法求解下题:
已知
,
,若![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32ccbe255a7d973e1041d1476152b4dc.png)
求
的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2a9344f4fca7b9779ca7720e5277ea6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21c7501096f4be07c98e97e29db21a21.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/407e4330cfdd5cd0bcfd4f3bd1a898e6.png)
甲:由基本不等式得
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f3d79e354cf1cf6c5bb0d043b68d07a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21c7501096f4be07c98e97e29db21a21.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca151609ac905d7afb1029e46871eb8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/421b46658c918a524d2bac634a43439a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c1b90fe86747dc4b2db35a84a3fa1f45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91aabebca1d156f88f56fd50f9fe5bbe.png)
乙:因为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21c7501096f4be07c98e97e29db21a21.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08677c8308807e4dca6fd9410d301a39.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ec42d8fad3691c5174f28306ddd63af.png)
同学们,请通过思考用合适的方法求解下题:
已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08115d6d9f876dea921a4d32260ff1fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/061813f1ec633c5c4c393c4de7938322.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32ccbe255a7d973e1041d1476152b4dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c915b4ce31fabfd4703c547291ad9277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43895441ab985675e2facdedf18575dc.png)
您最近一年使用:0次
名校
4 . 已知
,求
的最小值.
甲、乙两位同学的解答过程分别如下:
以上两位同学写出的结论一个正确,另一个错误.
请先指出哪位同学的结论错误,然后再指出该同学解答过程中的错误之处,并说明错误的原因.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08115d6d9f876dea921a4d32260ff1fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/47ca887e14ecf4b832ac9cd21affce91.png)
甲、乙两位同学的解答过程分别如下:
甲同学的解答: 因为 ![]() 所以 ![]() 上式中等号成立当且仅当 ![]() 即 ![]() 解得 ![]() 当 ![]() ![]() 所以当 ![]() ![]() | 乙同学的解答: 因为 ![]() 所以 ![]() ![]() ![]() 上式中等号成立当且仅当 ![]() 即 ![]() 解得 ![]() 所以当 ![]() ![]() ![]() |
请先指出哪位同学的结论错误,然后再指出该同学解答过程中的错误之处,并说明错误的原因.
您最近一年使用:0次
2021-01-03更新
|
808次组卷
|
3卷引用:北京市第二次普通高中2020-2021学年高二学业水平考试合格性考试数学试题
北京市第二次普通高中2020-2021学年高二学业水平考试合格性考试数学试题(已下线)专题02 基本不等式求和的最小值-2021-2022学年高一《新题速递·数学》(人教A版2019)黑龙江省鸡西市第四中学2022-2023学年高一上学期期中考试数学试题