# What is 5sqrt(-64) + 4sqrt4?

Jun 25, 2018

$\textcolor{b l u e}{8 \left(5 i + 1\right)}$

#### Explanation:

Note that $\sqrt{- 64}$ can only be evaluated as a complex number: $i \sqrt{64}$

$5 \sqrt{- 64} + 4 \sqrt{4}$

$\textcolor{w h i t e}{\text{XXX}} = 5 i \sqrt{64} + 4 \sqrt{4}$

$\textcolor{w h i t e}{\text{XXX}} = 5 i \cdot 8 + 4 \cdot 2$

$\textcolor{w h i t e}{\text{XXX}} = 5 i \cdot 8 + 8$

$\textcolor{w h i t e}{\text{XXX}} = 8 \left(5 i + 1\right)$