考研数学二真题
一、选择题:1~10小题,每小题5分,共50分.下列每题给出的四个选项中,只有一个选项是符合题目要求的.(1)x \rightarrow 0时,a(x),β(x)是非零无穷小量,给出以下4个命题:若\alpha(x)\sim \beta(x),则\alpha ^{2}(x)- \beta ^{2}(x);其中真命题是:()(A)(B).(C).(D)(2)\int _{0}^{2}dy \int _{y}^{2} \frac {y}{ \sqrt {1+x^{3}}}dx=()(A)\frac { \sqrt {2}}{6}.(B)\frac {1}{3}(C)\frac { \sqrt {2}}{3}.(D)\frac {2}{3}.(3)f(x)在x=x_{0}处二阶可导,以下说法正确的是()(A)若在x=x_{0}的某个邻域内f(x)单调增,则f'(x_{0})>0(B)若f'(x_{0})>0,则在x=x_{0}的某个邻域内f(x)单调增(C)若在x=x_{0}的某个邻域内f(x)图像是凹的,则f''(x_{0})>0(D)若f''(x_{0})>0,则在x=x_{0}某个邻域内f(x)图像是凹的(4)设函数f(t)连续,令F(x,y)= \int _{0}^{x-y}(x-y-t)f(t)dt则()(A)\frac { \partial F}{ \partial x}= \frac { \partial F}{ \partial y}, \frac { \partial ^{2}F}{ \partial x^{2}}= \frac { \partial ^{2}F}{ \partial y^{2}}.(B)\frac { \partial F}{ \partial x}= \frac { \partial F}{ \partial y}, \frac { \partial ^{2}F}{ \partial x^{2}}=- \frac { \partial ^{2}F}{ \partial y^{2}}(C)\frac { \partial F}{ \partial x}=- \frac { \parti