设 n 阶方阵 A, B 满足 AB=0, B neq 0，则必有().A. A=0B. A 为可逆方阵C. |B| neq 0D. |A|=0

函数的性质有界性、单调性、奇偶性、周期性。

设随机变量X的分布律为 (x=k)=dfrac (k)(c) k=1 ... n ,则常数c的取值()-|||-A. dfrac (n(n+1))(2) B. dfrac (2)(n(n+1)) C. dfrac (n(n+1))(3) D. dfrac (3)(n(n+1))

已知向量组:0 0 2 0-|||-α1= 1 α2= 1 ,α3= 0 ,α4= 1-|||-1 2 1 0(1)向量组0 0 2 0-|||-α1= 1 α2= 1 ,α3= 0 ,α4= 1-|||-1 2 1 0线性____ ; (2)向量组0 0 2 0-|||-α1= 1 α2= 1 ,α3= 0 ,α4= 1-|||-1 2 1 0线性_____;(3)向量组0 0 2 0-|||-α1= 1 α2= 1 ,α3= 0 ,α4= 1-|||-1 2 1 0线性_____.

(4) lim _(xarrow 0)(({e)^x+x)}^dfrac (1{x)}.

4.不用计算,验证下列积分之值为零,其中C均为单位圆周 |z|=1.-|||-(1) (int )_(c)^dzdfrac (dz)(cos z);-|||-(2) (int )_(c)dfrac (dz)({z)^2+2z+2};-|||-(3) (int )_(c)dfrac ({e)^2dz}({z)^2+5z+6};-|||-(4) (int )_(c)^zcos (z)^2dz.

3.对于函数y=sin(tan x)-tan(sin x)(0le xle pi)，x=(pi)/(2)是____. (A.)连续点 (B.)第一类间断点 (C.)可去间断点 (D.)第二类间断点

初等变换解下列方程组 2x+3y+z=4 x-2y+4z=-5 3x+8y-2z=13 4x-y+9z=-6

(9) lim _(xarrow +infty )dfrac (ln (1+dfrac {1)(x))}(arctan x)-|||-()

求下列函数的微分:-|||-(1) =dfrac (1)(x)+2sqrt (x);-|||-(2) =xsin 2x;-|||-(3) =dfrac (x)(sqrt {{x)^2+1}};-|||-(4) =(ln )^2(1-x);-|||-(5) =(x)^2(e)^2x;

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