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[单选题]
设a、b为常数,则有D(aX+b)=()。
A.a2D(X)+b
B.a2D(X)
C.aD(X)+b
D.aD(X)
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A.a2D(X)+b
B.a2D(X)
C.aD(X)+b
D.aD(X)
A.设c是常数,则D(C)=0
B.设X是随机变量,C是常数,则有D(CX)=C2D(X)
C.设X是随机变量,C是常数,则有D(X+C)=D(X)
D.若X和Y相互独立,则有D(X+Y)=D(X)+D(Y)
A.a=1/σ,b=μ/σ
B.a=σ,b=σμ
C..a=-1/σ,b=μ/σ
D..a=-1/σ,b=-μ/σ