设
相互独立且服从相同的分布，
，记
，其中a，b为非零常数，则当Y服从自由度为2的
的分布时常数a，b的值为（）
A.
B.
C.
D.
设相互独立且服从相同的分布，，记，其中a，b为非零常数，则当Y服从自由度为2的的分布时常数a，b的值为（）
A.
B.
C.
D.
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)_(
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
设随机变量x1,x2,x 3,x4相互独立,且有 ((x)_(i))=i,-|||-((x)_(i))=5-i;i=1,2,3,4, 设-|||-=2(x)_(