Question

I need help with 2 math problems. Complex Numbers

1. Which expression is equal to (8−3i)−(6+i)?

14−4i
2−4i
2−2i
14−2i

2. Multiply.

(5+2i)(4−3i)

Enter your answer, in standard form, in the box.

Answer 1

You add, subtract and multiply complex numbers exactly as you do with variables: you sum like terms, recalling that
`i^2=-1`

So, you have

`(8-3i)-(6+i) = 8-3i-6-i = 8-6-3i-i = 2-4i`

And

`(5+2i)(4-3i) = 20-15i+8i-6i^2 = 20-7i+6 = 26-7i`