设二维随机变量(X,Y)~N(0,1,12,22, ρ)求:(1)当ρ=0时,E(X-2Y+1),D(X-2Y+1)(2)当ρ=

设二维随机变量(X,Y)~N(0,1,12,22, ρ)
求:(1)当ρ=0时,E(X-2Y+1),D(X-2Y+1)
(2)当ρ=-1/2时,E(Y2-XY),D(X-2Y).
【正确答案】: