设_(1),(X)_(2),(X)_(3),(X)_(4)独立同分布，服从分布_(1),(X)_(2),(X)_(3),(X)_(4) ，记_(1),(X)_(2),(X)_(3),(X)_(4)，则 _(1),(X)_(2),(X)_(3),(X)_(4)的密度函数_(1),(X)_(2),(X)_(3),(X)_(4)

设_(1),(X)_(2),(X)_(3),(X)_(4)相互独立且服从相同的分布，_(1),(X)_(2),(X)_(3),(X)_(4)，记_(1),(X)

设_(1),(X)_(2),(X)_(3),(X)_(4)是取自总体_(1),(X)_(2),(X)_(3),(X)_(4)的样本,_(1),(X)_(2),(

) (x)_(1)+4(x)_(2)-2(x)_(3)+8(x)_(4)=2 -(x)_(1)+2(x)_(2)+3(x)_(3)+4(x)_(4)=1 (x)

设非齐次线性方程组 ) (x)_(1)+2(x)_(3)+(x)_(4)=2 (x)_(1)+(x)_(2)+(x)_(3)+4(x)_(4)=a (x)_(

用消元法解下列线性方程组:-|||- x1+3x2+5x3-4x4 =1, x1+3x2+2x3-2x4+x5=-1, x1-2x2+x3-x4-x5=3, x

关于方程组_(1)-2(x)_(2)+3(x)_(3)-4(x)_(4)=4 _(1)-2(x)_(2)+3(x)_(3)-4

求二次型 ((x)_(1),(x)_(2),(x)_(3))=4({x)_(2)}^2-3({x)_(3)}^2+4(x)_(1)(x)_(2)-4(x)_(1

2.解方程组 ) (x)_(1)+(x)_(2)+(x)_(3) (x)_(1)+(x)_(2)-(x)_(3)-(x)_(4)=1 5(x)_(1)+5(

1.已知方程组 ) (x)_(1)+(x)_(2)+(x)_(3)+(x)_(4)=2 3(x)_(1)+2(x)_(2)+(x)_(3)+(x)_(4)=a

设X1,X2,X3,X4,X5是来自正态总体X1,X2,X3,X4,X5的样本.(1) 求C使统计量X1,X2,X3,X4,X5服从X1,X2,X3,X4,X5