解题方法
1 . 已知函数
给出下列四个结论:
①当
时,
;
②若
存在最小值,则a的取值范围为
;
③若
存在零点,则a的取值范围为
;
④若
是减函数,则a的取值范围为
.
其中所有正确结论的序号是________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ebe96b300085ce5604e6c0a21a6992d.png)
①当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3b4d795709b0abcf47bceec2250f2f9b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57773e33670190531389702ec3a3de29.png)
②若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5e58768fc0df02f60aa54d00fe063c52.png)
③若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8898d2159c9309333db4431e066b376.png)
④若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c92083b0dc465138ec13031b9f4a62b.png)
其中所有正确结论的序号是
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名校
解题方法
2 . 已知
.
(1)若
,且
,求
的最小值;
(2)求证:函数
在
上单调的充要条件是
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e8d2133a1f584e8c8dbb02137f2eeb3.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d87cd4403487962c38c8707ba3ab3fa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5974d33b8ae80e89bf167f919200c41.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3b7c26095538dfcfd897155c157e7483.png)
(2)求证:函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/51c530f4b7491b95acb8ce3eef9aa09d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6c1756b564bf1d998d8179637011c88.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9de7887607fc09c5b0965c2e22e035fe.png)
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解题方法
3 . 如图所示,现有一个直角三角形材料,
,想要截得矩形CDEF,点E在边AB上,记矩形CDEF的面积为S,
的面积为T.已知
,设
,
,则( )
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/8/71d8244e-cb49-4275-b100-7cef1c8dc54e.png?resizew=118)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ed8f7d3d7043d4b1eb98fc5c4e2fcd3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c105d6ba18fbb0581fb982175e2eac9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cced8982712dd0ed53b56af71f4bf31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b483174c3f73ae0112a49f2f2e2b3e4b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50349b20b5e209c4afbba96aa76b5e75.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/8/71d8244e-cb49-4275-b100-7cef1c8dc54e.png?resizew=118)
A.![]() | B.![]() |
C.当S取最大值时,![]() | D.当S取最大值时,![]() |
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4 . 试分别解答下列两个小题:
(1)已知
的定义域为
,集合
在区间
上为增函数
,求
;
(2)解关于
的不等式
.
(1)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16b90d6ec42c5792667c239df00b67a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e64703d2bff8a9cfe7088ff09d5ed687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fe0d8080b2326afe8867da3ab5ddf43.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4ca8bdc812627d925f00ed7c145d696.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8fdbfa7a63fdf5717d40c8c9a73ec160.png)
(2)解关于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7103a5b63b539d01026152ad4f780299.png)
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