非齐次线性方程组Ax=b中,系数矩阵A和增广矩阵的秩都等于4,A是4×6矩阵,则( )A. 无法确定方程组是否有解。B. 方程组有无穷多解。C. 方程组有唯一解。D. 方程组无解。

已知随机变量X1和X2的概率分布为-|||-X1 -1 0 1 X2 0 1-|||-pi dfrac (1)(4) .dfrac (1)(2) dfrac (1)(4) pi .dfrac (1)(2) dfrac (1)(2)-|||-且 {X)_(1)(X)_(2)=0} =1 。-|||-(1)求X1和X2的联合分布律;-|||-(2)问X1和X2是否独立?

若f(x)在点x0处有定义,且在该点处的左、右极限都存在并相等而且都等于f(x0),则f(x)在x0处连续.

(7)已知 P(A)=0.4 , P(B)=0.3 , (A|B)=0.5, 则 P(A-B)= __

(2)对于事件A,B,下列命题正确的是 ()-|||-A.若A,B互不相容,则A,B也互不相容-|||-B.若A,B相容,则A B也相容-|||-C.若A,B互不相容,且概率都大于零,则A,B也相互独立-|||-D.若A,B相互独立,则A,B也相互独立

设二维随机变量(X,Y)的分布律为-|||-Y 0 1 2-|||-0 dfrac (1)(4) 0 dfrac (1)(4)-|||-1 0 dfrac (1)(3) 0-|||-2 dfrac (1)(12) 0 dfrac (1)(12)-|||-(1)求 X=2Y ;-|||-(2) cot (x-1,x)

#求过程#高数题！！！！救救孩子吧！！！(19) int tan sqrt (1+{x)^2}cdot dfrac (xdx)(sqrt {1+{x)^2}}-|||-(20) int dfrac (arctan sqrt {x)}(sqrt {x)(1+x)}dx;-|||-21 int dfrac (1+ln x)({(xln x))^2}dx;-|||-(22 int dfrac (dx)(sin xcos x);-|||-(23)∫cosxsinx-|||-(24)|cos^3xdx-|||-(25) int (cos )^2(omega t+varphi )dt;-|||-bigcirc (16)int sin 2xcos 3xdx;-|||-(27) int cos xcos dfrac (x)(2)dx;-|||-(28)|sin5xsin 7xdx;-|||-(29)int (tan )^3xsxcxdx;-|||-(30) int dfrac (dx)({e)^x+(e)^-x}-|||-(3) int dfrac (1-x)(sqrt {9-4{x)^2}}dx;-|||-(32) int dfrac ({x)^3}(9+{x)^2}dx;-|||-(33) int dfrac (dx)(2{x)^2-1};-|||-int dfrac (dx)((x+1)(x-2)):-|||-(35) int dfrac (x)({x)^2-x-2}dx;-|||-36) int dfrac ({x)^2dx}(sqrt {{a)^2-(x)^2}}(agt 0) :-|||-(77 int dfrac (dx)(xsqrt {{x)^2-1}};-|||-(38) int dfrac (dx)(sqrt {{({x)^2+1)}^3}}:-|||-(39) int dfrac (sqrt {{x)^2-9}}(x)dx;-|||-40 int dfrac (dx)(1+sqrt {2x)};-|||-(41) int dfrac (dx)(1+sqrt {1-{x)^2}};-|||-(42) int dfrac (dx)(x+sqrt {1-{x)^2}};-|||-(43) int dfrac (x-1)({x)^2+2x+3}dx;-|||-(44) int dfrac ({x)^3+1}({({x)^2+1)}^2}dx.

设连续型随机变量服从参数的指数分布，求的概率密度函数。

(8) lim _(xarrow dfrac {pi )(2)}dfrac (tan x)(tan 3x)

齐次线性方程组中,系数矩阵A的秩等于2,已知A是 times 4 矩阵,则-|||-A 方程组有非零解-|||-B 方程组无解-|||-C 方程组只有零解-|||-D 方程组有唯一解

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