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构造距离巧求多元函数最值
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作者 白志锋 《高中数学教与学》 2002年第6期61-62,共2页
在高中数学习题中,经常遇到求多元函数的最值,其方法可用换元法、判别式法、重要不等式法等.本文用构造距离法求解,供参考.一、构造两点间的距离例1(第二届“希望杯”全国数学邀请赛试题)以实数x。
关键词 数学 构造距离 解题方法 多元函数 最值
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The Spatial-temporal Distribution and Their Statistical Characteristics of Foreshocks in the Yunnan Region
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作者 Zhao Xiaoyan Sun Nan Su Youjin 《Earthquake Research in China》 CSCD 2016年第2期166-176,共11页
We analyzed 223 earthquakes with M 1〉 5.0 that occurred in the Yunnan region during 1965 - 2014, among which 74 ( about 33. 2 % ) had foreshocks. There are great differences in foreshock populations in different te... We analyzed 223 earthquakes with M 1〉 5.0 that occurred in the Yunnan region during 1965 - 2014, among which 74 ( about 33. 2 % ) had foreshocks. There are great differences in foreshock populations in different tectonic blocks: the most abundant foreshocks occurred in the Lancang-Gengma and Tengchong-Baoshan blocks, which have the most abundant foreshocks in the Yunnan region. The predominant magnitude difference, time interval and spatial distance are 0. 5 -2. 9, within 10 days and within 20km, respectively. These characteristics can be used to forecast the mainshock after the identification of a foreshock. 展开更多
关键词 Yunnan region Foreshock Mainshock Magnitude difference
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从解法比较看直观想象素养的价值与培育
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作者 沈良 《数学通讯》 2021年第12期31-34,共4页
本文以“构造距离探求最值”教学研究为例,探讨直观想象在数学解题中的价值.谈谈如何运用直观想象建立问题的直观模型,探索问题解决的思路.
关键词 直观想象 构造距离 探求最值 解法比较 数形统一 结构特征
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