Do the operation and express the answer in a + bi form.
$( 5 + \sqrt { - 16 } ) ( 4 - \sqrt { - 4 } )$
A)28 - 5 i
B)- 28 + 6 i
C)- 5 + 6 i
D)5 - 6 i
E)28 + 6 i

Question

Do the operation and express the answer in a + bi form. 
 $( 5 + \sqrt { - 16 } ) ( 4 - \sqrt { - 4 } )$  
A)28 - 5 i
B)- 28 + 6 i
C)- 5 + 6 i
D)5 - 6 i
E)28 + 6 i

Quizplus · Accepted Answer

First, simplify the square roots of negative numbers using $i$ where $i = \sqrt{-1}$. So, $\sqrt{-16} = 4i$ and $\sqrt{-4} = 2i$. Then, multiply the expressions: $(5 + 4i)(4 - 2i) = 20 - 10i + 16i - 8i^2$. Since $i^2 = -1$, this simplifies to $20 + 6i + 8 = 28 + 6i$.

Do the Operation and Express the Answer in a (5+−16)(4−−4)( 5 + \sqrt { - 16 } ) ( 4 - \sqrt { - 4 } )(5+−16​)(4−−4​)

Do the Operation and Express the Answer in a $( 5 + \sqrt { - 16 } ) ( 4 - \sqrt { - 4 } )$