Question

what is the product of the complex numbers (-3i+4) and (3i+4) ?
A) 1
B) 7
C) 25
D) -7 + 24i
E) 7 + 24i

Answer 1

i times-ed the two together and got -9i + 16...
maybe i need to add

Answer 2

then id get 8

Answer 3

use \(\large \bf (a+b)(a-b)=a^2-b^2\) property

Answer 4

\[\large \bf (4+3i)(4-3i)=4^2-(3i)^2\]

Answer 5

awesome! that helped a lot! at least i know were to start now. thanks!

Answer 6

so far got... 16+12i+12-9i^2 = 16 -9i^2

Answer 7

correct !

Answer 8

so what is the value of \(\large \bf i^2\)?

Answer 9

eather (x-1) + (x+1) or add it with the other i^2

Answer 10

well \[\large \bf i=\sqrt{-1}\]

Answer 11

so what would be \(\large \bf i^2\) then ?

Answer 12

√-9i^3 = -3 and 3

Answer 13

ops ^2