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 #
