Question

Multiply (4 + i)(1 − 5i). 9 − 19i −1 − 19i 4 − 5i2 4 − 19i − 5i2

Answer 1

(4 + i)(1 - 5i)

First, expand to get rid of parentheses.
$4 - 20i + i + 5$
Second, gather the like terms which contain the same variables. 
$(4+5) + (-20i + i)$
Third, add 4 + 5.
$9 + (-20i + i)$
Fourth, subtract -20i + i.
$9 - 19i$

Answer: 9 - 19i