单选题设A，B为n阶可逆矩阵，则______．A．存在可逆矩阵P1，P2，使得为对角矩阵B．存在正交矩阵Q1，Q2，使得为对角矩阵C．存在可逆矩阵P，使得P-1(A+B)P为对角矩阵D．存在可逆矩阵P，Q，使得PAQ=B

单选题设f(x)在(-∞，+∞)内连续且严格单调增，f(0)=0。常数n为正奇数，并设F(x)=，则下列判断正确的是______。A．F(x)在(-∞，0)内严格单调增，在(0，+∞)内也严格单调增B．F(x)在(-∞，0)内严格单调增，在(0，-∞)内严格单调减C．F(x)在(-∞，0)内严格单调减，在(0，+∞)内严格单调增D．F(x)在(-∞，0)内严格单调减，在(0，+∞)内也严格单调减

单选题讨论曲线y=4lnx+k与y=4x+ln4x的交点个数．

单选题设随机变量X与Y都服从0-1分布，且X，Y相互独立， P(X=0，Y=0)=1/6，P(X=1，y=0)=1/12， P(X=0，Y=1)=a，P(X=1，Y=1)=6，则______． A．a=1/15，b=25/36 B．a=25/36，b=1/18 C．a=1/2，b=1/4 D．a=1/6，b=1/12

单选题______A．B．C．D．

单选题已知函数f(x)在(-∞，+∞)上二阶可导，且f″(x)＞0，，则当x＞1时，f(x)A.单调减少且大于零；B.单调减少且小于零；C.单调增加且大于零；D.单调增加且小于零．

单选题设A为4×3矩阵，η1，η2，η3是非齐次线性方程组Ax=β的3个线性无关的解，k1，k2为任意常数，则Ax=β的通解为()．

单选题设，则f"(1)=______A．B．C．D．

单选题设ξ为函数f(x)=arcsinx在区间[0，b]上使用拉格朗日中值定理中的“中值”，则极限=A．．B．．C．．D．．

单选题You're busy filling out the application form for a position you really need, let's assume you once actually completed a couple of years of college work or even that you completed your degree. Isn't it tempting to lie just a little, to claim on the form that your diploma represents a Harvard degree? Or that you finished an extra couple of years back at State University? More and more people are turning to utter deception like this to land their job or to move ahead in their careers, for personnel officers, like most Americans, value degrees from famous schools. A job applicant may have a good education anyway, but he or she assumes that chances of being hired are better with a diploma from a well-known university. Registrars at most well-known colleges say they deal with deceitful claims like these at the rate of about one per week. Personnel officers do check up on degrees listed on application forms, then. If it turns out that an applicant is lying, most colleges are reluctant to accuse the applicant directly. One Ivy League school calls them "impostors". Another refers to them as "special cases". One well-known West Coast school, in perhaps the most delicate phrase of all, says that these claims are made by "no such people". To avoid complete lies, some job-seekers claim that they "attended" or "were associated with" a college or university. After carefully checking, a personnel officer may discover that "attending" means being dismissed after one semester. It may be that "being associated with" a college means that the job-seeker visited his younger brother for a football weekend. One school that keeps records of false claims says that the practice dates back at least to the turn of the century--that's when they began keeping records, anyhow. If you don't want to lie or even stretch the truth, there are companies that will sell you a fake diploma. One company, with officers in New York and on the West Coast, will put your name on a diploma from any number of nonexistent colleges. The price begins at around twenty dollars for a diploma from "Smoot State University". The prices increase rapidly for a degree from the "University of Purdue". As there is no Smoot State and the real school in Indiana is properly called Purdue University, the prices seems rather high for one sheet of paper.

单选题设二次型f(x1，x2，x3)=xTAx，其矩阵A满足A3=A，且行列式|A|＞0，矩阵A的迹trA＜0，则此二次型的规范形为A．B．C．D．

单选题设函数f(x)=(x-2)|x(x-2)|，则 A.f(x)在点x=0，2处都不可导； B.f(x)在点x=0，2处都可导； C.f(x)在点x=0处可导，而在点x=2处不可导； D.f(x)在点x=0处不可导，而在点x=2处可导．