How do you simplify #(-6-8i)(-3+8i)#?

2 Answers
Jacob
Jun 6, 2017

#82-24i#

Explanation:

You can just multiply everything out as in regular brackets, remembering that #i^2 = -1#.
So the expansion of #(-6-8i)(-3+8i)# is:
#(-6)(-3) + (-6)(8i) + (-8i)(-3) + (-8i)(8i)#
#= 18 - 48i + 24i -64i^2#
#= 18 - 64i^2 + (-48+24)i#
#= 18 + (-64)*(-1) -24i#
#= 18 + 64 -24i #
#= 82 - 24i#

Jim G.
Jun 6, 2017

#82-24i#

Explanation:

#"expand the brackets using FOIL"#

#rArr(-6-8i)(-3+8i)#

#=18-48i+24i-64i^2larr i^2=-1#

#=18-24i+64#

#=82-24i#

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