共查询到20条相似文献，搜索用时 62 毫秒
1.
在高三的一次课上，笔者先点评了作业中的一道题，该题是2010年江苏省高考第18题．
题目在平面直角坐标系xOy中，如图1，已知椭圆等x^2/9＋y^2/5=l的左、右顶点为A、B，右焦点为F．设过点T（t，m）的直线TA、TB与椭圆分别交于点M（xl，y1）、N（x2，v2），其中m〉0，yl〉0，y2〈0．（1）设动点P满足PF^2-PB^2=4，求点P的轨迹；（2）设x1=2，x2=1/3，求点T的坐标；（3）设t=9，求证：直线MN必过X轴上的一定点（其坐标与m无关）． 相似文献
2.
谭智平 《衡阳师范学院学报》1996,(6)
对只有一个变点模型x（i／n）=f（i／n）＋ε（i／n），其中，f（t）={J1 S1（t－t0），0＜t≤t0，J2 S2（t-t0），t0＜I≤1，ε（i／n），…，ε（n／n）独立同分布，J1，J2，S1，S2，t0为未知参数，讨论了变点t0处，跳变度（J2-J1）和坡变度（S2－S1）的联合分布。 相似文献
3.
张筱蘅 《西安文理学院学报》1999,(3)
一、问题的提出1．若函数f（X,y）在点（x0,y0）沿X轴正向和负向的方向导数存在且相等,那么f（X,y）在点（x0,y0）关于X的偏导数f'x（x0,y0）是否一定存在？2．如果把条件加强为f（x,y）在点（x0,y0）治任意方向的方向导数都存在,这时能否断定f（x,y）在该点有关于X的偏导数f'x（x0,y0）？二、讨论由方向导数的定义：f（X,y）在点（X。,y。）沿方向l的方向导数为：放沿X轴正向了一（1,0）的方向导数为：沿X轴负向三’一（－1,0）的方向导数为：又由函数在一点偏导数存在的充分必要条件：在该点左、右偏导数存在且相等,… 相似文献
4.
叶顺亚 《中学数学教学参考》2010,(11):47-47,56
1试题及简解
2010年高考数学江苏卷第18题：如图,在平面直角坐标系xOy中,已知椭圆x2/9＋y2/5=1的左、右顶点为A、B,右焦点为F．设过点T（t,m）的直线TA、TB与此椭圆分别交于点M（x1,y1）、N（x2,y2）,其中m〉0,y1〉0,y2〈0． 相似文献
5.
对于n阶线性做分方程1997年赵白云对常系数几（t）方程（1）给出一种解法“‘．今对变系数a小）方程（1）给出特解的求法．不妨弓队做分算子D一如,并记F（D）一Za;（t）H,则方程（1）表示为引理在式F（D）中,对常数人有关系F（D）［e“xj一e“F（D＋A）［习．（3）定理方程（l）有型如x一e“。（J为常数）特解的先要条件是于是,方程（l）有待解x一e“z的充要条件是（4）成立．此时,取函数Z一／（是为常数）,则当j＞在时,D卜」一0,于是（）等价于推论1方程（1）有持解x—x‘e“（k,A为常数）的充要条件是（）成立．现若令人… 相似文献
6.
利用临界点理论研究以下二阶系统
{u（t）＋q（t）u（t）= F（t, u（t））,
u（0）-u（T）=u（0）-eQ（T）u（T）=0, a.e. t∈[0, T ]
的周期解的存在性。在非线性项F（t,x）=F1（t,x）＋F2（x）满足假设（A）及F1（t,x）,F2（x）分别满足一定有界性条件下,通过使用极小作用原理获得了一个新的存在性定理。 相似文献
7.
（2010年江苏高考数学卷第18题）在平面直角坐标系中，已知椭圆x^2/9＋y^2/5=1的左右顶点为A、B，右焦点为F，设过点T（t，m）的直线TA、TB与椭圆分别交于点M（x1，y1）、N（x2，y2），其中m〉0，y1〉0，y2〈0． 相似文献
8.
9.
记f（x,y）＝Ax2＋Bxy＋Cy2＋Dx＋Ey＋F（A、B、C不全为零）．定理若过一点（a,b）的直线被二次曲线f（x,y）＝0截得的弦（不过有心曲线的中心）的中点为（X0,y0）,则证明方程f（x,y）＝0可变形为令ZAX。十河。十p一人‘（。,y。）,ZO。＋B。＋E一人’（x。,y。）,设过点（a,b）及点（x。,y。）的直线方程为将（2）代入（l）,整理得易知该方程有两个不等的实根x1及x。,依韦达定理及中点坐标公式得试举几例说明定理的应用例1给定双曲线X’一会一1,过点A（2,1）的直线l与所给双曲线交于两点产;和P。,求线段P;P。… 相似文献
10.
张昌斌 《郧阳师范高等专科学校学报》1994,(2)
5、广义拟变分不等式 定理5.1 设E,F都是Hausdorff拓扑线性空间,F局部凸（F~o分离F的点）,XE是非空仿紧闭凸集,YF非空凸,S:X→2_Y上h一半连续且具非空闭（紧）凸值,T:Y→X是可逆的,保凸的和开的,P:Y→2~（F~o）单调具非空值且对任一一维线段∠F,P│∠∩Y由F的拓扑到F~o的弱~o拓扑下半连续,再设 （i）△_o={x∈X:sup sup Re（u,T~（-1）x-y）>0）}是X的相对开集, y∈S（x） u∈P(y) （ii）存在y_o∈Y及E的非空紧子集KX使得 inf Re（w,T~（-1）x-y_o）>0,y_o∈S（x）,x∈X/K w∈P（T~（-1）x） 则存在∈X使得T~（-1）∈S且 sup Re（u,T~（-1）-y（≤0,y∈S（5.1） u∈P（T~（-1）） 证令φΨ:XxY→R, φ（x,y）=sup Re（u,T~（-1）x-y）,Ψ（x,y）=inf Re（w,T~（-1）x 相似文献
11.
12.
《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
13.
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
14.
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
15.
16.
RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
17.
Rajesh Kanoi 《海外英语》2007,(1):52
Today, Sunday morning, I sit thinking and typing at my computer. My thoughts are in my homeland, India and my body is in China. The body is here and mind there for a good reason. Mr. Hu is president and I am resident and both are in each other's countries (what a difference the absence of one small letter makes!). Mr. Hu will return in a few days and I will stay on longer. 相似文献
18.
正A One day a pig went to the stable(马棚)to see his good friend,an oldhorse,and was going to stay there forthenight.Night came and it was time forsleep.The pig went into the straw heap(稻草堆)and lay comfortably.A longtime passed,but the horse was stillstanding there and did not move.Thepig asked the horse why he did not go tosleep."Standing like this is the begin-ning ofsleeping,"answered the horse. 相似文献
19.
《今日中学生》2014,(9)
正1.Any fool can count the seeds in an apple.Only God can count all the apples in one seed.2.Happy families are all alike;every unhappy family is unhappy in its own way.3.Memories are the key not to the past,but to the future.4.Sometimes in the dark you see what you want to see.5.There is a great difference between 相似文献
20.
《重庆大学学报(英文版)》2014,(2)
正Scope and Policy The Journal of Chongqing University-English Edition(JCQU-E)is a peerreviewed journal publishing research articles in multiple disciplines of science and technology,covering civil and environmental engineering,chemical engineering,biotechnology,mechanical and electrical engineering,computer and data processing,mining,metallurgy,materials science,and interdisciplines thereof. 相似文献