Question

How do you simplify `(3+5i)(2+15i)`?

Answer 1

`color(magenta)(=> -69 + 55i`

Explanation:

`(3 + 5i) * (2 + 15i)`

`=> 3*2 + 3*15i + 2*5i + 5i * 15i`, removing braces.

`=> 6 + 45i + 10i + 75i^2`, multiplying term by term.

`=> 6 - 75 + 45i + 10i`, regrouping terms as also `i^2 = -1`

`=> -69 + 55i`