一个长方体的长减少
,宽不变,高增加
,就得到一个与原长方体体积相同的正方体,求原长方体的表面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38387ba1cadfd3dfc4dea4ca9f613cea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
更新时间:2024-03-24 18:38:32
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解答题-作图题
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适中
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【推荐1】图1是第七届国际数学教育大会的会徽,会徽的主体是由如图2所示的一连串直角三角形演化而成的,
(n是正整数)
,
,
,
,…,
的面积分别记为
,
,
,…,
.认真分析下列各式,解答下列问题.
,
;
,
;
,
________;
,
;
…
________,
________.(n是正整数)
(1)补全上述横线处内容;
(2)在线段
,
,
,…,
中,长度为整数的线段共有________条;
(3)若
,求
的长度.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/245b5e868cefb834a762c83974bad899.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0204f76cda5ea4ced714588be1efeaa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15536798ab47cadce6d4d80f542051f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bcbc88b4ce21109c35f68372f56d2336.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fdc52a10f5f86a3c49ff2f9286d44362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c5059a849f276bd9cd2234ce03f01f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e097c8d4c948de063796bd19f85b3a9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e0bd63f55069a3bc870915010b39225.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6899bf9cadae2ccdb14cbc87d4f280ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/699d0a7506a6752c0e46322327ae9d56.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a41ee1f8d4b35e625e3421d2800cf3e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34fc0166eff48b308e01e904654f6525.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b7f90d19c423cd47bb4ea2fd51e21f18.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df6eed76dd84935fa030801bc9cd9822.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef354e5c5ff828cc8d27c71badd40f98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/395d7fa9cae714d1276376323ce621b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe2d2bf20356e34d2759fa887bfc2505.png)
…
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20c25071879961a5670897e90f5b96e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04c2864e2ec3416cc4c081ac1f71a0af.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/17/e96f75c8-3e3e-413e-8216-3d83f8db1505.png?resizew=352)
(1)补全上述横线处内容;
(2)在线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4195334905e2f190f958dbf5951456f8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c76916c6ff302cf4fb4b6ace5bb3a95.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/181f7b988095b7285557491c7bb2fb5c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/751e5135671225d82f185079ddf4abfd.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db9a09296066a3e650ed3ea0bc6bb910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/337d0dc1076cfdb02ffb40bf4dac0d90.png)
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解答题-计算题
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【推荐2】嘉淇准备完成题目:计算:(▓![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8476d17b8eb190e31bc96658c8434d57.png)
, 发现系数“▓”印刷不清楚.
(1)他把“▓”猜成 3,请你计算:(3![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8476d17b8eb190e31bc96658c8434d57.png)
.
(2)他妈妈说:“你猜错了,我看到该题标准答案的结果是 0.”请你通过计算说明原题中“▓”是几?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8476d17b8eb190e31bc96658c8434d57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/007e447f26a36315e2bc0ed9ffee27c8.png)
(1)他把“▓”猜成 3,请你计算:(3
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8476d17b8eb190e31bc96658c8434d57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/007e447f26a36315e2bc0ed9ffee27c8.png)
(2)他妈妈说:“你猜错了,我看到该题标准答案的结果是 0.”请你通过计算说明原题中“▓”是几?
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适中
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名校
【推荐3】由
得,
;如果两个正数a,b,即
,则有下面的不等式:
,当且仅当
时取到等号.
例如:已知
,求式子
的最小值.
解:令
,则由
,得
,当且仅当
时,即
时,式子有最小值,最小值为4.
![](https://img.xkw.com/dksih/QBM/2021/3/20/2681997411524608/2682864786341888/STEM/af59a1c9-6951-4071-a741-02692de5adf3.png?resizew=368)
请根据上面材料回答下列问题:
(1)当
,式子
的最小值为______________;当
,则当
__________时,式子
取到最大值;
(2)用篱笆围一个面积为32平方米的长方形花园,使这个长方形花园的一边靠墙(墙长20米),问这个长方形的长、宽各为多少时,所用的篱笆最短,最短的篱笆是多少?
(3)如图,四边形
的对角线
、
相交于点O,
、
的面积分别是8和14,求四边形
面积的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c50ee6d453ad5a650c43a73aa03a311.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48fe5d9cbe4f83926f5c21912df67a2e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2684b72f9f38f5046c8ecd4280b7b14b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/759c09917e5728d75bf5cfdb5b4a807f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f22fec5a381ae8aca93d876e54c79de.png)
例如:已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08115d6d9f876dea921a4d32260ff1fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9929b4a95df4cb001be158a1600ae5e4.png)
解:令
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24f46bd9295bc707cdb2d7fec0d84d24.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c1ec5317c2642bca22a5814e21494acd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01cdc65f1068c9506046926a7724254e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41f1e3048c60441505af80599dba214f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/707ea658f3a9359f5740d5aab48f7948.png)
![](https://img.xkw.com/dksih/QBM/2021/3/20/2681997411524608/2682864786341888/STEM/af59a1c9-6951-4071-a741-02692de5adf3.png?resizew=368)
请根据上面材料回答下列问题:
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08115d6d9f876dea921a4d32260ff1fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13f40c24c64bbb0645fcf585f4e66872.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e541ea2f855f981c96207070683d388.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ec0618ae3a4fde6d6220010af229b9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09ef0bf09c764c7d9c7bc2054b40075e.png)
(2)用篱笆围一个面积为32平方米的长方形花园,使这个长方形花园的一边靠墙(墙长20米),问这个长方形的长、宽各为多少时,所用的篱笆最短,最短的篱笆是多少?
(3)如图,四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/866b81a8384cce4f24867baca2e6820c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a9a6eeeebf3cff569578d7366b755aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
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解答题-问答题
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【推荐1】一个长方体的长、宽、高分别为8厘米、6厘米、4厘米,现将其切成两个相同的小长方体,怎样切其表面积最大?求此时每个小长方体的表面积.
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解答题-问答题
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【推荐2】如图,用一根彩带捆扎一个长方体礼品盒,接头处的彩带长
.这根彩带长多少厘米?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea25d45a5dd98bf85b3dfd298aedec09.png)
您最近一年使用:0次