## Precalculus (6th Edition) Blitzer

The standard form of the expression $3i\left( 2+i \right)$ is $-3+6i$.
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 $-3+6i$.