2006高三·江苏·竞赛
1 . 设 a 、b 、c 为正数 , 记 d 为(a -b)2、(b -c)2、(c -a)2 中的最小数.
(1)求证 :存在 λ(0 <λ<1),使得d ≤λ(a2 +b2 +c2);
(2)求出使不等式 ①成立的最小正数 λ,并给予证明.
(1)求证 :存在 λ(0 <λ<1),使得d ≤λ(a2 +b2 +c2);
(2)求出使不等式 ①成立的最小正数 λ,并给予证明.
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2 . 如图所示,D是△ABC中,边BC的中点,K为AC与△ABD的外接圆O的交点,EK平行于AB且与圆O交于E,若AD=DE,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5974541cc9607d1a34be49fa1b43bb1b.png)
![](https://img.xkw.com/dksih/QBM/2020/5/11/2460515774578688/2460617066782720/STEM/dafd666bc8974dc0aded3da2d34ecb94.png?resizew=229)
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解题方法
3 . 已知函数
.对任意
,且
,求证:
(1)
;
(2)
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3b4201725a144562cc0f0da070603308.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85db25f0623bb097e5a57117df267011.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/26d8dafc71b106f39f4e15442220897b.png)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ca3ecbbaca8eeb1cfa8f4035f7d5726.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/400f3350d356149043b4590e2b4c8138.png)
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4 . 设k、l、c均为正整数,证明:存在正整数a、b满足
,且
,其中(a,b)表示a、b的最大公因数,
表示正整数m的所有不同正因子的个数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4bd0a2436ddb3505d7cef5937752d6de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acd450ba68b4f365390307deacce2b2a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/131072b8a777616f9019dd4e4e7ce083.png)
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5 . 证明:对任意x∈(-∞,0)∪(0,+∞),
,且等号成立的充要条件是
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92ce5d29f74028975fb2e8bc1fe24a57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a877181839d6cd64be7861712f781f06.png)
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6 . 在数列
中,已知
,
.求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33faf50aecb1379ea0b5b600549f6c1e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f3b0646a5af210f4d69945c9ea5a0e4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5d8e5ec00150c2504b1e06aa64d3f77.png)
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2010高三·江苏·竞赛
7 . 如图,
是半圆
上位于
轴上方的任意一点,
、
是直径的两个端点,以
为一边作正方形
,
、
分别与
交于点
、
.求证:
、
、
成等比数列.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5790ac31f0c1ee0ceebcec1af710001e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/12a477603f3f88c3b48352b6130f9ad5.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/7/719ba147-5c67-4b5b-9052-8a1aa3513176.png?resizew=168)
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8 . 已知点O为凸四边形ABCD内的一点,AO=OB,CO=OD,
,E、F、G分别是线段AB、BC、CD的中点,求证:
为正三角形.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb879cccf44dbf4d72c9a85906dfb5a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9756177ef0c7c685e0fc62077a1cd4e.png)
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9 . 将凸
边形
的边与对角线染上红、蓝两色之一,使得没有三边均为蓝色的三角形. 对
,记
是由顶点
引出的蓝色边的条数.求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/132df501fe16d9bed7ba8742084baa43.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c365eeee68c896623c8a9f4d1a4e0f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/233427826eb2233641fc3a9805f6d206.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d7f2c72ab559a0615db4c51327b78d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87a89cc62d9ff292fbfc3e1496106892.png)
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