3()9={(…x)x=1 x;岂能属于随机变量! 正确求解 ={(x2…,x)x∈R,=12,…,n (2)L(x,…,x)=I 2 2兀O (2) (3)E(X)=4,D(X)=,E(S2)=a6-3 (1)  = (x1 ,  , xn ) xi R, i =1,2,  ,n 2 2 2 ( ) 1 1 2 1 ( , , )    − − = =  i x L x x e n i  n (2)  =  = − − n i i n x n e 1 2 2 2 1 2 ( ) (2 ) 1     (3) ( ) , ( ) , 2 n E X D X  =  = 2 2 E(S ) = (1)  = (x1 ,  , xn ) xi  X, i =1,2,  ,n i x 岂能属于随机变量！ 正确求解