![](https://i.imgur.com/fL0i7Ug.jpg)
Re: [理工] [通訊] 隨機程序
![](https://i.imgur.com/fL0i7Ug.jpg)
![](https://i.imgur.com/Z2PLsAY.jpg)
: 想問第d小題
: 題目是證明X1和Y2是否成不相關
: http://i.imgur.com/8d2gBY6.jpg
![](https://i.imgur.com/8d2gBY6.jpg)
: 我的作法是上圖
: 可以得到E[X1Y2]=E[X1]E[Y2]=0
: http://i.imgur.com/JFUzmV1.jpg
![](https://i.imgur.com/JFUzmV1.jpg)
: 可是解答卻這樣寫
: 我哪裡算錯了??
: E[X1Y2]不能相等與E[X1]E[Y2]嗎?
: 可是他們不是獨立?
先說E[X1(t)Y2(t)]不等於0 你的0上一行是正確的,但為何突然=0?!?!
然後E[X1(t)]E[Y2(t)]是0沒錯 所以兩者相關
然後你的觀念要加強 獨立可以推得不相關沒錯!但是 那是原變數獨立
新變數是由原變數組合而成,並不一定會獨立 如果是老手,一看到新變數就知道不會獨
立了!
加油唷,有問題歡迎再問
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※ 編輯: wx19930509 (42.78.146.123), 08/26/2015 18:37:20
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