共查询到20条相似文献，搜索用时 62 毫秒
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在导数的学习中 ,我们常常会遇到下面一些问题 :例 1 已知 f(x) =kx3-x2 + 13 kx-16在R上单调递增 ,则k的取值范围是 ( )(A)k >1 (B)k≥ 1(C)｜k｜ >1(D)｜k｜≥ 1错解 f′(x) =3kx2 -2x+ 13 k ,依题设 ,对一切x ∈R ,f′(x) >0 .∴3k>0Δ =4-4 · 3k·13 k<0 ,∴k >1,选A .正解 依题设 ,对一切x∈R ,f′(x) ≥0 ,应选B .错因辨析 我们知道 ,对一切x∈R ,f′(x) >0是 f(x)在R上单调递增的充分不必要条件 .该题中 ,f(x)在R上单调递增的充要条件是对一切x∈R ,f′(x)≥ 0 .值得提醒的是 ,并不是对一切函数 f(x) ,f′(x)… 相似文献
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定义设P(x)为m次多项式,则以a_n=P(n)为项的数列称为m次多项式P(x)的数列。问题设a_n为m次多项式P(x)的数列,问如何求和sum from k=1 to n(a_k)=sum from k=1 to nP(K)。为此我们先给出引理1 设f(x)为m次多项式,则一阶差分Δf(x)=f(x+1)-f(x)为m-1次多项式,命题是显然成立的,故证略。引理2 若P(x)=a_mx~m+…+a_1x+x_0,α_m≠0为一m次多项式。则有f(x)=β_m+1x~(m+1)+…+β_1x,使得Δf(x)=P(x)。证明时只要算出Δf(x)=f(x+1)- 相似文献
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在高等代数中,有关于多项式除法的一个定理:设f(x)和g(x)是F[x]中的任意两个多项式,并且g(x)≠0,那么在F[x]中可以找到多项式q(x)和r(x),使f(x)=g(x)·q(x)+r(x),这里,或者r(x)=0,或者r(x)的次数小于g(x)的次数, 相似文献
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胡璋剑 《湖州师范学院学报》2001,23(6):1-8
对可允许的权函数ω：[0,1）→（0，∞），加权Bergman空间L^Pα↓，ω上的范数定义作‖f‖P，ω＝｛∫D|f(z)|^Pω(|z|)dm(z)｝^1/p。我们证明，对0＜p＜∞和f∈H（D），‖f‖p,ω-|f(0)| ｛|∫′（z）^pΨ(|z|)^pω(|z|)dm(z)｝^1/p。由此我们给出函数算子Tg:f→∫z↑0↓f(t)g′(t)dt在L^Pα↓，ω上有界的一个充分条件。 相似文献
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王兆雄 《苏州教育学院学报》1994,(1)
在复数域C上,设f(x)=C_nx~n C_(n-1)x~(n-1) … C_1x C_0C_i∈C,(i=0,1,2,…,n)是一个复系数多项式,则称 其中是C_i的共轭复数 为f(x)的共轭多项式。 在复数域C上,复系数多项式f(x)与其共轭多项式的最大公因式(f(x),(?)(x))是一个实系数多项式。 事实上,设d(x)=(f(x),(?)(x)),则d(x)|f(x),d(x)|(?)(x),所以(?)(x)|(?)(x),(?)(x)|(?)(x),即(?)(x)|f(x),因此,(?)(x)|(f(x),(?)(x))即(?)(x)|d(x),d(x)|(?)(x),所以d(x)=(?)(x),这说明d(x)的系数为实数,因此,(f(x),(?)(x))是一个实系数多项式。 关于共轭多项式,有一些很有趣的性质,本文仅讨论其中的一个。 定理:若复数α=a bi(a,b∈R)是复系数多项式f(x)的一个根,则α的共轭复数 相似文献
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设 f(x)=a_0x~n a_1x~(n-1) … a_(n-1)x a_n是n次实系数多项式,如果当x取非负整数值时,f(x)都是整数,则称f(x)是整值多项式。一个多项式什么时候是整值多项式呢?本文介绍一种简单的判定方法。先介绍一个引理。引理。设f(x)为n次多项式,则f(x)能唯一地表示成下面的形状: 相似文献
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定义记fo(x)是给定的一个多项式,记f1(x)=f0‘(x).将f0(x)除以f1(x)所得余式变号记为f2(x),即f0(x)=f1(x)q(x)-f2(x)(deg f2(x)相似文献
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研究Hermite插值余项E(x)=f(x)-H(x)=m1!f(m)(ξ)ωm(x).在一定条件下估计‖f(m)(x)‖∞和‖ωm(x)‖∞的上界.提出一种在给定精度ε下计算f(x)的算法,同时给出数值实验. 相似文献
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本文将给出一个有关组合数与多项式的有趣的恒等式。对于p次多项式f(x)及组合数C_n~i,可构造出组合恒等式; sum from i=0 to n(-1)~iC_n~if(i)=0(1)这里的p为非负整数,且p相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献