Evaluate the expression ( 1 + 2 i ) ( − 2 − 1 i ) and write the result in the form a + b i .

- 5i.

Step-by-step explanation:

( 1 + 2 i ) ( − 2 − 1 i )

= 1 * -2 + 1*-1i + 2i*-2 - 2i*1i

= -2 - i - 4i - 2i^2           i^2 = -1 so we have:

-2 - 5i +2

= 0 - 5i

= -5i.

it shoild be o

step-by-step explanation:

1. sometimes

2. never true

3. sometimes

step-by-step explanation:

these are pretty self explanatory if you know what supp right and com angles are