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中考内容要求实数与代数式所考查的知识有:有理数,倒数,相反数,绝对值,数轴的运用,实数的大小比较,乘方,科学记数法,有效数字,二次根式,实数的估算,列代数式,解释代数式,求代数式的值,探求数与式的规律. 相似文献
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著名数学家华罗庚说过:善于退,足够的退,退到最原始而不失去重要的地方,是学好数学的一个诀窍.这里所谓的退,当然不是逃跑,而是养精蓄锐,蓄势待发,是在为进寻求途径,即以退为进.它的实质是借助转化的数学思想,把复杂的问题简单化,运动的问题静止化,高维问题低维化,变量问题常量化,抽象问题具体化,代数问 相似文献
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在很久很久以前,有两个年轻人,一起去遥远的地方寻找幸福和快乐,一路上风餐露宿,历尽艰辛,在即将到达目的地时,遇到了一条风急浪高的大河.对于如何渡过这条河,两人有不同的意见:一个人建议砍伐附近的树造一条木船渡过河去,另一个人则认为这么高的浪,这么湍急的水流,这么宽的河面,无论造多大的船都不可能渡过这条河,与其自寻烦恼和死路,不如等这条河干了,再轻轻松松地走过去. 相似文献
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现实的数学课堂教学中,我们不难发现,看上去精彩纷呈的一堂课,学生、老师都表现得很积极,课堂气氛也热闹非凡,其实这样的课堂未必高效,而有时看似很普通的常规课,却往往透着高效.有人总认为高效课堂是名师的专利,对于普通老师来说,上好常规课,做到有效就已经是很努力的事情了,高效课堂是遥不可及的海市蜃楼,其实,在教学过程中,只要我们把功夫花在课前,抓住课堂这块教学的主阵地,落实课后反思,高效课堂也能触手可及. 相似文献
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香港海洋公园里有一条大鲸鱼,虽然重达8600 kg,却不但能跃出水面6.6m,还能向游客表演各种杂技.面对这条创造奇迹的鲸鱼,有人向训练师请教训练的秘诀.训练师说,在最初开始训练时,我们会先把绳子放在水面之下,使鲸鱼不得不从绳子上方通过,每通过一次,鲸鱼就能得到奖励.渐渐地,我们会把绳子提高,只不过每次提高的幅度都很小,大约只有2 cm,这样鲸鱼不需花费多大的力气就有可能跃过去,并获得奖励.于是,这条常常受到奖励的鲸鱼,便很乐意地接受下一次训练.随着时间的推移,鲸鱼跃过的高度逐渐上升,最后竟然达到了6.6m. 相似文献
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浅谈图形语言在解题中的巧用 总被引:2,自引:0,他引:2
美国数学家斯蒂恩说:"如果一个特定的问题可以转化为图形,那么,思想就整体地把握了问题,并且能创造性地思索问题的解法."这就表明,解题时若能挖掘问题的几何意义,配以适当的图形,就有利于分析题中数量之间的关系,丰富表象,拓宽思路,化繁为简,化难为易,迅速找出解决问题的方法,提高分析和解决问题的能力,取得以简驭繁的效果. 相似文献
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In this paper,the perturbations of the Moore–Penrose metric generalized inverses of linear operators in Banach spaces are described.The Moore–Penrose metric generalized inverse is homogeneous and nonlinear in general,and the proofs of our results are different from linear generalized inverses.By using the quasi-additivity of Moore–Penrose metric generalized inverse and the theorem of generalized orthogonal decomposition,we show some error estimates of perturbations for the singlevalued Moore–Penrose metric generalized inverses of bounded linear operators.Furthermore,by means of the continuity of the metric projection operator and the quasi-additivity of Moore–Penrose metric generalized inverse,an expression for Moore–Penrose metric generalized inverse is given. 相似文献
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The problems of perturbation and expression for the generalized inverses of closed linear operators in Banach spaces and for the Moore-Penrose inverses of closed linear operators in Hilbert spaces are studied. We first provide some stability characterizations of generalized inverses of closed linear operators under T-bounded perturbation in Banach spaces, which are exactly equivalent to that the generalized inverse of the perturbed operator has the simplest expression T+(I+δTT+)-1. Utilizing these results, we investigate the expression for the Moore-Penrose inverse of the perturbed operator in Hilbert spaces and provide a unified approach to deal with the range preserving or null space preserving perturbation. An explicit representation for the Moore-Penrose inverse of the perturbation is also given. Moreover, we give an equivalent condition for the Moore-Penrose inverse to have the simplest expression T†(I+δTT†)-1. The results obtained in this paper extend and improve many recent results in this area. 相似文献
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研究范畴中态射的加权Moore-Penrose逆,利用态射广义分解的性质给出了态射加权Moore-Penrose逆存在的一些充要条件,导出了态射的加权Moore-Penrose逆的表达式,推广了态射Moore-Penrose逆的相应结果. 相似文献
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The Moore-Penrose inverse is an important tool in algebra.This paper shows that the MoorePenrose inverse is also an effcient technique in determining the minimal martingale measure if a security price follows a semi-martingale which satisfies some structure condition.We extend a result of Dzhaparidze and Spreij concerning the Moore-Penrose inverse to the case that the Moore-Penrose inverse of any matrix-valued predictable process is still predictable.Furthermore,we obtain an explicit formula of the minimal martingale measure by employing the Moore-Penrose inverse.Specifically,the minimal martingale measure in a generalized Black-Scholes model is found. 相似文献
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An expression for the Moore-Penrose inverse of certain singular circulants by S.R. Searle is generalized to include all circulants. Similar expressions are given for the Moore-Penrose inverse of block circulants with circulant blocks, level-q circulants, k-circulants where |k|=1, and certain other matrices which are the product of a permutation matrix and a circulant. Expressions for other generalized inverses are given. 相似文献
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讨论Fuzzy矩阵的Moore-PenrOSe逆,给出一些Moore-Penrose逆存在的充要条件以及Moore-Penrose逆的划画。 相似文献
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The concept of the Moore-Penrose inverse in an indefinite inner product space is introduced. Extensions of some of the formulae in the Euclidean space to an indefinite inner product space are studied. In particular range-hermitianness in completely characterized. Equivalence of a weighted generalized inverse and the Moore-Penrose inverse is proved. Finally, methods of computing the Moore-Penrose inverse are presented. 相似文献
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张荣娥 《纯粹数学与应用数学》2008,24(3)
主要研究了二元Boolean矩阵A的加权Moore-Penrose逆的存在性问题,给出了二元Boolean矩阵A的加权Moore-Penrose逆存在的一些充分必要条件,并讨论了加权Moore-Penrose逆存在时的若干等价刻画及惟一性问题. 相似文献