imaginary/ complex numbers

[har]

Im not sure what steps to take to slove this equation.
(-4i)(2-3i)
do I multiply -4i throughout or use the foil method.
I'm just not sure how to start

 

[Loren]

What you have written is not an equation. It is an expression. An equation has an equal sign someplace. Should there be one?
Possibly you want to expand the expression. If so, handle it as you would a(b+c) = ab + ac, then simplify your result realizing that i[sup:26muf1sc]2[/sup:26muf1sc] = -1.

 

[har]

Your right I meant to say expression. I used that formula and this is what i did and what I came up with.
(-4i)(2)+(-4i)(-3i)
-8i+12i^2
-8i-12
-12-8i

 

[masters]

Your right I meant to say expression. I used that formula and this is what i did and what I came up with.
(-4i)(2)+(-4i)(-3i)
-8i+12i^2
-8i-12
-12-8i

You did good, har!

 

[har]

Thanks a bunch!

 

[lookagain]

Your right I meant to say expression. I used that formula and this is what i did and what I came up with.
(-4i)(2)+(-4i)(-3i)
-8i+12i^2
-8i-12
-12-8i

You have correct steps, but if I want to show students (or myself) another helpful step,
then I would add a step (and space out your characters more) as:

\(\displaystyle (-4i)(2) - (4i)(-3i) =\)

\(\displaystyle -8i + 12i^2 =\)

\(\displaystyle -8i + 12(-1) =\)

\(\displaystyle -8i - 12 =\)

\(\displaystyle \boxed{-12 - 8i}\)