Someone tell me what I did wrong? I got this question wrong on a test and I am wondering how I should have done it differently.
Simplify the expression.

(3 + 2i)(4 – i)
12-3i+8i-2i^2
12+5i-2i^2
-2i^2+5i+12

Question

Someone tell me what I did wrong? I got this question wrong on a test and I am wondering how I should have done it differently.
Simplify the expression.

(3 + 2i)(4 – i) 
12-3i+8i-2i^2
12+5i-2i^2
-2i^2+5i+12

anonymous · Answer

you can still simplify further:
$$i^2 = -1$$

anonymous · Answer

Ohhh, I see, thanks.

anonymous · Answer

anytime you have the imaginary constant i raised to an even exponent it takes on a numerical value which is real

anonymous · Answer

$$i^1=i$$
$$i^2=-1$$
$$i^3 = -i$$
$$i^4= 1$$

i, -1, -i, 1 repeated for higher exponents