Posted by mada on .
(3+4i)(34i)

algebra maginary numbers 
Reiny,
just expand it as if the i was a variable
(3+4i)(34i)
= 9  12i + 12i 12i^2, now remember i^2 = 1
= 9  12(1)
= 9+12
= 21 
algebra maginary numbers 
mada,
wait when you factor it wouldnt it be 912i+12i16i^2

algebra maginary numbers 
Reiny,
of course, my silly error

algebra maginary numbers 
mada,
its totally cool you have helped alot :)