# How do you simplify # (2 - i )( 4 + i )#?

##### 1 Answer

Jan 21, 2016

9 - 2i

#### Explanation:

Expand the brackets (distributive law - using FOIL method )

so (2 - i )(4 + i )

# = 8 + 2i - 4i - i^2 = 8 - 2i - i^2 = 8 - 2i + 1# [ remembering that

# i^2 = - 1 ]#

#rArr (2 - i )(4 + i ) = 9 - 2i #