求不定积分[img=115x46]17da65382f8e1b9.png[/img]；（） A: x - (5*log(x + 1))/4 - (3*log(x - 3)) B: (5*log(x + 1))/4 - (3*log(x - 3)) C: x - (5*log(x + 1))/4 - (3*log(x - 3))/4 D: (5*log(x + 1))/4 - (3*log(x - 3))/4

公告：维护QQ群：833371870，欢迎加入！
公告：维护QQ群：833371870，欢迎加入！
公告：维护QQ群：833371870，欢迎加入！

2022-06-07 问题

求不定积分[img=115x46]17da65382f8e1b9.png[/img]；（） A: x - (5log(x + 1))/4 - (3log(x - 3)) B: (5log(x + 1))/4 - (3log(x - 3)) C: x - (5log(x + 1))/4 - (3log(x - 3))/4 D: (5log(x + 1))/4 - (3log(x - 3))/4

2022-06-04 问题

设(X,Y)的联合密度为[img=246x61]17de89815546a18.png[/img]，则EY=_, E(XY)=_. A: EY=4/5, E(XY)=7/5 B: EY=7/5, E(XY)=2/5 C: EY=3/5, E(XY)=1/2 D: EY=2/3, E(XY)=2/5

设(X,Y)的联合密度为[img=246x61]17de89815546a18.png[/img]，则EY=_____, E(XY)=_____. A: EY=4/5, E(XY)=7/5 B: EY=7/5, E(XY)=2/5 C: EY=3/5, E(XY)=1/2 D: EY=2/3, E(XY)=2/5

2022-06-14 问题

曲线|xy|+1=|x|+|y|所围图形的面积为 A: 1 B: 2 C: 3 D: 4 E: 5

2022-06-14 问题

曲线｜xy｜+1=｜x｜+｜y｜所围图形的面积为( )． A: 1 B: 2 C: 4 D: 3 E: 5

2022-07-26 问题

曲线｜xy｜+1=｜x｜+｜y｜所围图形的面积为( )． A: 1 B: 2 C: 4 D: 3 E: 5

2022-06-16 问题

运行下面代码输出的是： ds = { "a": 1, "a":2, "a": 3, "b": 4, "b": 5, "c": 6} print(len(ds)) A: 3 B: 4 C: 5 D: 6

2022-10-25 问题

设随机变量X,Y有E(X)= E(Y)=0, E(XY)= -1/8, D(X)= D(Y)=3/4, 则ρXY =____(a/b)

2022-06-08 问题

执行以下语句的结果：dict1={"x":1,"y":2,"z":3}dict2={"x":4,"a":5}dict1.update(dict2) A: {"x":1,"y":2,"z":3,"x":4,"a":5} B: {"x":4,"a":5,"x":1,"y":2,"z":3} C: 有重复项，结果有误！ D: {"x":4,"y":2,"z":3,"a":5}

执行以下语句的结果：dict1={"x":1,"y":2,"z":3}dict2={"x":4,"a":5}dict1.update(dict2) A: {"x":1,"y":2,"z":3,"x":4,"a":5} B: {"x":4,"a":5,"x":1,"y":2,"z":3} C: 有重复项，结果有误！ D: {"x":4,"y":2,"z":3,"a":5}

2022-05-29 问题

已知x²+xy=5,xy+y²=-4,求（1）x²-y²的值；（2）4x²+xy-3y²的值

2022-06-17 问题

设随机变量X,Y有D(X)= 9,D(Y)= 4,ρXY =1/3,则Cov(X,Y)=____

1 2 3 4 5 6 7 8 9 10