设X是取自总体 N（μ,σ2）的一个样本，μ 的无偏估计量是（ ）
A: 1/4·X1+2/4·X2
B: 2/4·X1+1/4·X2+1/4·X3
C: 1/4·X1+1/4·X2+1/4·X3
D: 2/4·X1+2/4·X2+1/4·X3
A: 1/4·X1+2/4·X2
B: 2/4·X1+1/4·X2+1/4·X3
C: 1/4·X1+1/4·X2+1/4·X3
D: 2/4·X1+2/4·X2+1/4·X3
举一反三
- 求不定积分[img=112x35]17da6538063a9e4.png[/img]； （ ） A: (x^4*log(x)^2)/4 + (x^4*(log(x) - 1/4))/ B: (x^4*log(x)^2)/4 - (x^4*(log(x) - 1/4))/8 C: (x^4*log(x)^2)/4 - (x^4*(log(x) - 1/4)) D: (x^4*log(x)^2)/4 + (x^4*(log(x) - 1/4))/8
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- 阅读下面程序,则disp语句所显示结果为()。x=1;while x~=5disp(x)x=x+1;end A: 1 3 2 4 B: 1 2 3 4 C: 2 3 4 5 D: 1 3 4 2
- 设矩阵，已知A的特征值是λ1=2，λ2=λ3=1，则（）。 A: x=-4，y=3 B: x=-4，y=-3 C: x=4，y=-3 D: x=4，y=3