名校
解题方法
1 . 为了求一个棱长为
的正四面体的体积,某同学设计如下解法.
解:构造一个棱长为1的正方体,如图1:则四面体
为棱长是
的正四面体,且有
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/6/16/6db5d8bf-a942-4eb1-b74e-0d41be5b6734.png?resizew=583)
(1)类似此解法,如图2,一个相对棱长都相等的四面体,其三组棱长分别为
,
,
,求此四面体的体积;
(2)对棱分别相等的四面体
中,
,
,
.求证:这个四面体的四个面都是锐角三角形;
(3)有4条长为2的线段和2条长为
的线段,用这6条线段作为棱且长度为
的线段不相邻,构成一个三棱锥,问
为何值时,构成三棱锥体积最大,最大值为多少?
[参考公式:三元均值不等式
及变形
,当且仅当
时取得等号]
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
解:构造一个棱长为1的正方体,如图1:则四面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68ac02c2f91cadb1e328bc6ab9b9c491.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6f878ffcff2ca25a434cbeea7d5c841.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/6/16/6db5d8bf-a942-4eb1-b74e-0d41be5b6734.png?resizew=583)
(1)类似此解法,如图2,一个相对棱长都相等的四面体,其三组棱长分别为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2967337e3fcb228dded64ab0c41a17e0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50690dab38f4512eb72e18b7f86cf6f6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4056761b8f826eeb6ad8c9a151d3c9c.png)
(2)对棱分别相等的四面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c220eadc312101e2fb89dfe920f7b30d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7de966c316db1013defc56372fcf814e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8d2530e7023b2345c651e8f53629ff1.png)
(3)有4条长为2的线段和2条长为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
[参考公式:三元均值不等式
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ffb6b373d2e672bb2afc8de547861a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4849ff71159df2bb9099b26065d81e1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44acc0ee22dc4b7750e8be825e7c1355.png)
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2021-07-15更新
|
814次组卷
|
2卷引用:重庆市西南大学附属中学2020-2021学年高一下学期期末数学试题
2 . 设函数
,
,函
,
,
,
.
(1)当函数
是奇函数,求
;
(2)证明
是严格增函数;
(3)当
是奇函数时,解关于
的不等式.
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b191b62a98e346ac0b5d7eefdc47a5fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/665e92c365730c03e3bc94aed79a1058.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ed29f55445faaf6b2e7a32c9f79713f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abc10f552cd07b67c3b0efb21a378931.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d2f632a968a5481d065742671a00397.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99074f989e74d5ff306b4b7b7a379c1f.png)
(1)当函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1938c093dd2fbcb752d0eb7a18d143b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
(2)证明
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/942c2141d01bde6b48210c56a17fc75e.png)
(3)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1938c093dd2fbcb752d0eb7a18d143b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4cbf479c39081caf83ad7a451c9ba7f.png)
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3 . (1)先化简,再求值:
,其中
.
(2)先化简;再求值:当
时;求代数式![](https://staticzujuan.xkw.com/quesimg/Upload/formula/efee6c509313fac5387d910b661e5ff1.png)
(3)关于
的代数式
的值与
无关,求
的值.
(4)求值:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbb05868da64493f9a2c4dc3871011a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aa8f878ab71705ccae99bfc9a32c8b8e.png)
(2)先化简;再求值:当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ad202ed8c2aea4e055f9dc62f581bd2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/efee6c509313fac5387d910b661e5ff1.png)
(3)关于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73f9c5f751a21b4c026144b6f2782e24.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
(4)求值:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/efe924053218702aa2a43139bf611c2f.png)
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4 . (1)先化简,再求值:
,其中
;
(2)已知
是关于
的一元二次方程
的一个实数根,求方程的另一个根及
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73ff724e11a45ab29f7db5bb3d0120bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/200f24e682c93e02a87f3f9d57dc5d40.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53156a895d6231cfdc10e1d017d4ece9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64cba0c6d78a4f35cb9924d259531372.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
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5 . (1)化简:
.
(2)求值:
.
(3)设
,
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9425b2d567b729467fec9498c183e32d.png)
(2)求值:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/349678bf311bf77582444d12907a4428.png)
(3)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5aca7f0097fc0562c40375ce6756d56.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1bb6f1d6a053b78c221624885791f66.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a2893bd2a2299d8180f45494ba593d1.png)
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6 . (1)化简求值:
;
(2)若
,
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4947ab0e3b3eaa7a3d0d16b38e6cd582.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7326ea56be82bd616fec7e6aa3c884c8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73b3739f2cddb3045d7d39d1f88a2f0f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac767b538138b81695e2636177f5dc14.png)
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7 . 当
为何值时,不等式
恰有一个解.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/399e7902cf319a4ecc40aebda074eda4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e17a1c30f62f3dce43df74c310679a5.png)
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解题方法
8 . 函数
,
(1)解关于
的不等式
;
(2)若
,
①若
,求证
;
②画出
的图象.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ec5ee992e4d7904e80e246a908fe9051.png)
(1)解关于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/018857ec6e498113b3b12a730d9313da.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5e342b2932a0414a3221e961c0e116aa.png)
①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/764f981a79d9850e2fd2afb79940da50.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0e297f6897dec36236986df208904d9.png)
②画出
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a1cfb60420ff7e72c1b9d64f69ae063.png)
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9 . 已知关于
的函数
.
(1)解关于
的不等式
;
(2)集合
,集合
,若对
,使得
,求实数
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4fd5867c8933db1829cd96e62b1aecf.png)
(1)解关于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/604dd9ed21f5a5651587c7765ba3988b.png)
(2)集合
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f48315a36487b2caf947394a660cc978.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9d8f299bb2cc71f6958008dd99597cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d8517978fb4995883af8125bf91a0c4c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1292c47f62023b747f1a4bd615c75284.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
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解题方法
10 .
,用
表示
,
的较小者,记为
,若
,
,则下列说法正确的是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d96b743603ab1c10330622f16db78dbe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/531bcdb6324cb5a759301daddf9768c0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4669810732b633b60dbeaf0bf57204f6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9772ebd6f5dc607d082d1b7b36a3f0de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df18da1ecd1a83afc4544ee71f00c56b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/176c4a9de5a11fa2574fb00cd316a8db.png)
A.![]() |
B.函数![]() |
C.不等式![]() ![]() |
D.若a,b,c是方程![]() ![]() |
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