Question

8i/4-2i
The answer is -4 + 8i/5 but i don't how to get to it....HELP

Answer 1

when you divide by a complex number, think Complex conjugate
multiply top and bottom by 4+2i

Answer 2

i did that and i do not know what i am doing wrong

Answer 3

32i+16i^2

Answer 4

thats for

Answer 5

to

Answer 6

the top

Answer 7

(4-2i)(4+2i)

notice that looks like (a+b)(a-b) which equals (a^2 - b^2)
or you could multiply it out.

what do you get for the bottom?

Answer 8

12

Answer 9

(4 - 2i) (4+ 2i) the long way:
4*4 + 4*2i -2i*4 - 2i*2i
16 +8i -8i -4i^2
8i - 8i is 0
16 - 4*i^2
by i*i is -1
16 - 4 * -1
16+4
20

shorter way:
4^2 + 2^2 (the i*i will make the - turn into a positive)
= 20

Answer 10

oh thank you i get it

Answer 11

btw, I would not multiply out things up top right away. It is simpler to cancel things
\[ \frac{ 8 i (4+2i)}{20} \]
divide top and bottom by 4
\[ \frac{ \cancel{8}2 i (4+2i)}{\cancel{20}5}
\]
now multiply it out
\[ \frac{8i +4i^2}{5} = \frac{-4+8i}{5} \]

Answer 12

okay thanks i will look for that on the next few problems : )