、erasure (11)erasure (-)dfrac (erasure {1)}(2)((x)_(1),(x)_(2),(x)_(3))-|||-(x)_(1)+b(x)_(2)+c(x)_(3)=0,-|||-((X)_(1))=E((X)_(2))=E((X)_(3))=d,-|||-((X)_(1))=Nar((X)_(2))=var((X)_(3))=(sigma )^2.-|||-其中a,b,c,d,σ^2均为常数,求相关系数ρ12,ρ23,ρ 13·-|||-39.设随机变量X与Y都只能取两个值,试证:X与Y独立与不相关是等价的.-|||-40.设随机变量X服从区间 (-0.5,0.5) 上的均匀分布, =cos X, 则X与Y有函数关系.试求Cov-|||-(X,Y).-|||-41.设二维随机变量(X,Y)服从单位圆内的均匀分布,其联合密度函数为-|||-p(x,y)= ,{x)^2+(y)^2lt 1 (x)^2+(y)^2geqslant 1 .-|||-试证X与Y不独立且X与Y不相关.

(B) dfrac (1)(2)(X)_(1)+dfrac (1)(2)(X)_(2)-|||-(C) dfrac (1)(2)(X)_(1)+dfrac (1

函数(x)=dfrac (1)(3)(x)^3+dfrac (1)(2)(x)^2的单调递增区间是( )A．(x)=dfrac (1)(3)(x)^

int dfrac ({x)^3}({(1+{x)^2)}^2}dx=A.int dfrac ({x)^3}({(1+{x)^2)}^2}dx=B.int df

dfrac (1)(x) C. -dfrac (1)({x)^2} D. dfrac (2)({x)^3}

int (x+2)xdx=()A、dfrac(1)(3)(x)^3+(x)^2+CB、dfrac(1)(3)(x)^3+2(x)^2+CC、dfrac(1)(2

int dfrac (2{x)^3+2x+3}({x)^2+1}dx=(x)^a+b(x)+C 则 cdot b(x)=

((X)_(1)+(X)_(2)+(X)_(3))/3 b.X1-|||-c. ((X)_(1)+(X)_(2))/2 d. (2(X)_(1)+(X)_(2)

(x)=dfrac (1)(3)(x)^3-(x)^2-8x+1的单调增加区间是( )(x)=dfrac (1)(3)(x)^3-(x)^2-8x+1(x)=d

... +({X)_(n)}^2)-|||-;(5) (mu )^2+dfrac (1)(3)((X)_(1)+(X)_(2)+(X)_(3))-|||-;(6

17、单选 lim _(xarrow infty )dfrac (sin 3x+2x)(sin 2x-3x)-|||-A dfrac (1)(3)-|||-B