Question

nothing

Answer 1

its the same as if it was x instead of i.

Answer 2

You would apply FOIL.
What you did is like saying that (x+1)(x+1)=2x+2
Instead, we do (x*x)+(1*x)+(1*x)+(1*1) which simplifies to x^2+2x+1
Do you understand what I'm trying to say?

Answer 3

... That was an example. What I meant is that you should expand it first by multiplying and then simplify it.
(1 + 2i)(5 − 3i) would become (1*5)+(-3i*1)+(2i*5)+(-3i*2i)

Answer 4

11+7i

Answer 5

Hmmm .... how is it that your getting 11? I think shes not understanding how the answer is getting 11. Can you explain.

Answer 6

She isn't really responding...

Answer 7

oh well.
(1 + 2i)(5 − 3i) --FOIL--> (1*5)+(-3i*1)+(2i*5)+(-3i*2i)
>5-3i+10i-6i^2
\*
simplify as if i is a variable
*\
>5-7i-6i^2
\*
Note that i= sqrt(-1) and that i^2= sqrt(-1)^2= -1
*\
>5-7i-6(-1)
>11-7i

Answer 8

Thats super explained! Thanks!

@Grazes