Let a be any constant.
\(V[a]=0\)
Proof : Let a be any constant.
\begin{eqnarray*}V[a]&=&E[\left(a-E[a]\right)^{2}]\\&=&E[(a-a)^{2}]\ \ \ (\text{∵}\ \ E[a]=a\ \ )\\&=&E[0]=0\end{eqnarray*}
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Let a be any constant.
\(V[a]=0\)
Proof : Let a be any constant.
\begin{eqnarray*}V[a]&=&E[\left(a-E[a]\right)^{2}]\\&=&E[(a-a)^{2}]\ \ \ (\text{∵}\ \ E[a]=a\ \ )\\&=&E[0]=0\end{eqnarray*}