Answer
The standard form of the expression $3i\left( 2+i \right)$ is $-3+6i$.
Work Step by Step
Consider the expression, $3i\left( 2+i \right)$
Use the distributive property.
$\begin{align}
& 3i\left( 2+i \right)=3i\left( 2 \right)+3i\left( i \right) \\
& =6i+3{{i}^{2}}
\end{align}$
Use the definition ${{i}^{2}}=-1$.
$\begin{align}
& 3i\left( 2+i \right)=6i+3\left( -1 \right) \\
& =-3+6i
\end{align}$
Therefore, the standard form of the expression $3i\left( 2+i \right)$ is $-3+6i$.
