FRM I Quantitative 老师您好,不太清楚这个式子的推导,可以推导给我看一下吗,谢谢老师解答。 cov(ax+by,cx+dy)=acV(x)+bdV(y)+(ad+bc)cov(x,y),if x and y are correlated.添加评论 0 0 1 个答案 已采纳答案 orange品职答疑助手 · 2018年06月29日 同学你好,推导过程见下图 添加评论 0 0...
D(aX+bY) =a^2 D(X)+b^2 D(Y)+2abCov(X,Y) 分析总结。 我知道dxydxdycovxy这个公式想知道更一般的公式是什么样子的结果一 题目 D(aX+bY)=?还有D(aX-bY)=?这里那个D()是方差我知道D(X+Y)=DX+DY+Cov(X,Y)这个公式 想知道 更一般的公式是什么样子的.X和Y不相互独立哦 答案 D(...
∴cov(X+Y,X-Y)=σ1²-σ2²另外这道题出错了，没有正确答案，原因如下：由题得ρ=0,则X,Y独立且都服从正态分布,现在我讨论下一般的结论：设U=aX+bY V=cX+dY (abcd是常数) 显然U，V(在ab不全为0且cd不全为0时)也都属于正态分布 ﹡可证明当ad≠bc时，U和V...
六、协差矩阵记住以下公式:D(aX+bY )=a2DX+b2DY+2abcov(X,Y)D(X±Y)=DX+DY±2cov(X,Y)cov(Z,aX+bY)=acov(Z,X)+bcov(Z,Y)例:已知随机向量(X,Y)的协差矩阵V为计算随机向量(X+Y, X-Y)的协差矩阵。 相关知识点: 试题来源: 解析 解:DX=4, DY=9, COV(X,Y)=6 D(X+Y)=...
假设随机变量X、Y的期望值和方差均存在，分别为E(X)、E(Y)和D(X)、D(Y)。∵D(aX+bY)=D(aX)+D(bY)+2COV(aX,bY)，而，D(aX)=a²D(X)、D(bY)=b²D(Y)、COV(aX,bY)=abCOV(X,Y)，∴D(aX+bY)=a²D(X)+b²D(Y)+2abCOV(X,Y)。供参考。cov...
由x与y相互独立,有cov(x,y)=0,故D(u)=D(ax+by)=a^2Dx+b^2Dy=(a^2+b^2)σ^2 D(v)=D(ax-by)=a^2Dx+b^2Dy=(a^2+b^2)σ^2,cov(u,v)=cov(ax+by,ax-by)=a^2Dx-b^2Dy=(a^2-b^2)σ^2 所以ρuv=(cov(u,v))/(根号下Du*根号下Dv)=(ac*根号下Dx*根号下Dy*ρxy)/...
CXLC10,CCL2,IL-11,IL-7, andCXCL8mRNAs were notably induced in the lung of mice injected with AAV-Lung-N, but relatively unaffected in the lung of mice injected with AAV-Lung-CT (Fig.1i). Interestingly, N-induced expression ofIL-1β,IL-6,TNF,CXLC10,CCL2,IL-11,IL-7, andCXCL8...
www.nature.com/scientificreports OPEN Inactivation of SARS‑CoV‑2 by a chitosan/α‑Ag2WO4 composite generated by femtosecond laser irradiation Paula Fabiana Santos Pereira1,2, Ana Carolina Alves de Paula e Silva3, Bruna Natália Alves da Silva ...
www.nature.com/scientificreports OPEN Inactivation of SARS‑CoV‑2 by a chitosan/α‑Ag2WO4 composite generated by femtosecond laser irradiation Paula Fabiana Santos Pereira1,2, Ana Carolina Alves de Paula e Silva3, Bruna Natália Alves da Silva ...
As shown in Figure 1a, a DC power source (CX-600A, Chengdu Chuangyu Xinjie Technology Co., Ltd., Sichuan, China) was used to drive the CAP torch (Figure 1c), which could produce variable voltage between 5–60 kV, 400 W output. The CAP torch electrode tip was connected as the ...