问答题设f(x)，g(x)在x0的某邻域内具有二阶连续导数，且，证明(1)y=f(x)及y=g(x)在点x0相切；(2)y=f(x)及y=g(x)在x0的某邻域中具有相同的凹凸性及在x=x0上有相同的曲率．

问答题设随机变量X的分布律为P{X=k)=p(1-p)k-1(k=1，2，…)，Y在1～k之间等可能取值，求P{Y=3)．

问答题设f(u,v)具有二阶连续偏导数，且满足，又g(x，y)=，求．

问答题设f(x)是多项式，且求f(x)．

问答题Discussion of the assimilation of Puerto Ricans (波多黎各人 ) in the United States has focused on two factors: social standing and the loss of national culture. In general, excessive stress is placed on one factor or the other, depending on whether the commentator is North American or Puerto Rican. Many North American social scientists, such as Oscar Handlin, Joseph Fitzpatrick, and Oscar Lewis, consider Puerto Ricans as the most recent in a long line of ethnic entrants to occupy the lowest rung on the social ladder. (46) Such a " socio demographic" approach tends to regard assimilation as a benign process, taking for granted increased economic advantage and inevitable cultural integration, in a supposedly egalitarian context. However, this approach fails to take into account the colonial nature of the Puerto Rican case, with this group, unlike their European predecessors, coming from a nation politically subordinated to the United States. (47) Even the "radical" critiques of this mainstream research model, such as the critique developed in Divided Society, attach the issue of ethnic assimilation too mechanically to factors of economic and social mobility and are thus unable to illuminate the cultural subordination of Puerto Ricans as a colonial minority. In contrast, the "colonialist" approach of island based writers such as Eduardo Seda- Bonilla, Manuel Maldonado-Denis, and Luis Nieves-Falcon tends to view assimilation as the forced loss of national culture in an unequal contest with imposed foreign values. There is, of course, a strong tradition of cultural accommodation among other Puerto Rican thinkers. The writings of Eugenio Fernandez Mendez clearly exemplify this tradition, and many supporters of Puerto Rico's commonwealth status share the same universalizing orientation. (48) But the Puerto Rican intellectuals who have written most about the assimilation process in the United States all advance cultural nationalist views, advocating the preservation of minority cultural distinctions and rejecting what they see as the submission of colonial nationalities. This cultural and political emphasis is appropriate, but the colonialist thinkers misdirect it, overlooking the class relations at work in both Puerto Rican and North American history. They pose the clash of national cultures as an absolute polarity, with each culture understood as static and undifferentiated. (49) Yet both the Puerto Rican and North American traditions have been subject to constant challenge from cultural forces within their own societies, forces that may move toward each other in ways that cannot be written off as mere "assimilation. " Consider, for example, the indigenous and Afro-Caribbean traditions in Puerto Rican culture and how they influence and are influenced by other Caribbean cultures and Black cultures in the United States. (50) The elements of compulsion and inequality, so central to cultural contact according to the colonialist framework play no role in this kind of convergence of racially and ethnically different elements of the same social class.

问答题设三阶实对称矩阵的秩为2，λ 1 =λ 2 =6是A的二重特征值，若α 1 =(1，1，O) T ，α 2 =(2，1，1) T ．α 3 =(-1，2，-3) T 都是A的属于特征值6的特征向量．

问答题设A为三阶实对称矩阵，且存在可逆矩阵使得又A的伴随矩阵A*有特征值λ0，λ0所对应的特征向量为α=(2，5，-1)T．

问答题设二维连续型随机变量(X，Y)在矩形区域D=(x，y)|0≤x≤2，0≤y≤1上服从均匀分布，令Z=max(X，Y)，求E(Z)与D(Z)。

问答题设X1，X2，…，Xn来自总体X的一个简单随机样本，X的密度函数为

问答题设u=f(x，z)，而z=z(x，y)是由方程z=x+yφ(z)所确定的隐函数，其中f具有连续偏导数，而φ具有连续导数，求du。

问答题计算，其中L为椭圆周．

问答题求，其中D：x2+y2≤π2．

问答题求下列曲面的面积：