Question

I have a problem here and made it half way (not sure how to do the rest)
(2-i)(-3+6i)
FOIL
I got:
-6 + 12 i +3 i - 6 i^2

Answer 1

What is i^2 ?

Answer 2

i squared

Answer 3

Are you multiplying complex numbers, such that \(i= \sqrt{-1}\)? If so, what does \(i^2=\)?

Answer 4

yes and i squared is -1

Answer 5

im not sure how I would combine like terms then plug in -1 for i squared

Answer 6

Right, so you can do a bit more simplification of your result. Combine the \(i\) terms, and change the \(i^2\) to \(-1\).

Answer 7

\[(2-i)(-3+6i) = 2*(-3)+2*6i-i*(-3) -i*6i = -6+12i + 3i -6i^2\]\[=-6+15i-6i^2\]Right?

Answer 8

Now substitute \(-1\) for \(i^2\):
\[-6+15i-6*(-1) = -6 + 15i + 6 = \]

Answer 9

(2-i)(-3+6i)
-6+12i+3i-6i^2 is when you foil.
-6+15i+6 the -6 and +6 cancel so you are left with your answer of;
15i

Answer 10

yes I see so the 6's cancel out

Answer 11

Yes (:

Answer 12

thanks so much!!! to you both