# How do you simplify (-7i)(4i)(-1+3i)?

Aug 23, 2016

$- 28 + 84 i$

#### Explanation:

distribute the bracket after multiplying the 2 terms outside the bracket.

$\Rightarrow - 28 {i}^{2} \left(- 1 + 3 i\right)$

$\textcolor{\mathmr{and} a n \ge}{\text{Reminder }} \textcolor{red}{| \overline{\underline{\textcolor{w h i t e}{\frac{a}{a}} \textcolor{b l a c k}{{i}^{2} = {\left(\sqrt{- 1}\right)}^{2} = - 1} \textcolor{w h i t e}{\frac{a}{a}} |}}}$

$\Rightarrow - 28 {i}^{2} \left(- 1 + 3 i\right) = 28 \left(- 1 + 3 i\right) = - 28 + 84 i$