设随机变量(X,Y)服从二维正态分布N([img=25x26]1803df51a14544f.png[/img],1;0,1;0), 记[img=142x53]1803df51ab25eca.png[/img]则EZ=____.(保留小数点后2位)

CBS

设 z=z(x,y)z=z(x,y) 是由方程 ez−xyz=0ez−xyz=0 确定的函数, 则 ∂z∂x= A: zx(z−1)zx(z−1) B: yx(1+z)yx(1+z) C: z1+zz1+z D: yx(1−z)yx(1−z)

哥伦比亚广播公司（CBS）

以下HDB3码中，哪些可以确定其中有误码 A: +1 0 0 0 -1 0 +1 -1 +1 0 0 +1 0 -1 +1 -1 0 0 -1 +1…… B: +1 0 0 -1 +1 0 0 0 +1 -1 0 0 -1 0 0 0 +1 0 0 +1 -1…… C: -1 0 0 0 -1 0 +1 0 0 0 +1 -1 +1 0 0 +1 0 0 -1 +1…… D: -1 0 +1 0 0 0 -1 +1 0 0 0 +1 -1 +1 -1 0 0 -1 +1 0 -1……

‍对HDB3码-1000+100-1000-1+1000+1-1+1-100-1+1-1进行译码，结果是（ ）。‌ A: 1 0 0 0 1 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 0 0 1 1 B: 1 0 0 0 1 0 0 1 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 C: 1 0 1 0 1 0 0 1 0 0 0 0 1 1 0 0 0 1 1 0 0 0 0 1 1 D: 1 0 0 0 1 0 0 1 0 0 0 0 1 0 0 1 1 0 0 0 0 0 0 1 1

编写程序，创建下列10*10的数组，数组边界全为1，里面全为0。 [[1 1 1 1 1 1 1 1 1 1] [1 0 0 0 0 0 0 0 0 1] [1 0 0 0 0 0 0 0 0 1] [1 0 0 0 0 0 0 0 0 1] [1 0 0 0 0 0 0 0 0 1] [1 0 0 0 0 0 0 0 0 1] [1 0 0 0 0 0 0 0 0 1] [1 0 0 0 0 0 0 0 0 1] [1 0 0 0 0 0 0 0 0 1] [1 1 1 1 1 1 1 1 1 1]]

已知磁感应强度为：B=3xex+（y-2z）ey-（y-mz）ez，则m的值应为（）。 A:  1 B:  2 C:  3 D:  4

编写程序，创建下列10*10的数组，数组边界全为1，里面全为0。 [[1 1 1 1 1 1 1 1 1 1] [1 0 0 0 0 0 0 0 0 1] [1 0 0 0 0 0 0 0 0 1] [1 0 0 0 0 0 0 0 0 1] [1 0 0 0 0 0 0 0 0 1] [1 0 0 0 0 0 0 0 0 1] [1 0 0 0 0 0 0 0 0 1] [1 0 0 0 0 0 0 0 0 1] [1 0 0 0 0 0 0 0 0 1] [1 1 1 1 1 1 1 1 1 1]] 提示：可以先创建全为0或者全为1的数组，再通过索引和切片机制进行修改

对信码1000100100001000011000011进行HDB3编码，结果可能是（ ）。 A: -1 0 0 0 +1 0 0 -1 0 0 0 -V +1 0 0 0 +V -1 +1 -B 0 0 -V +1 -1 B: +1 0 0 0 -1 0 0 +1 0 0 0 +V -1 0 0 0 -V +1 -1 +B 0 0 +V -1 +1 C: +1 0 0 0 -1 0 0 +1 0 0 0 +1 -1 0 0 0 -1 +1 -1 +1 0 0 +1 -1 +1 D: -1 0 0 0 +1 0 0 -1 0 0 0 +V +1 0 0 0 +V -1 +1 +B 0 0 -V +1 -1