Question

How do you multiply `(6-3i)(3-i)`?

Answer 1

`15-15i`

Explanation:

distribute the brackets using, for example, the FOIL method.

`rArr(6-3i)(3-i)=18-6i-9i+3i^2=18-15i+3i^2`

`color(orange)"Reminder "`

`color(red)(bar(ul(|color(white)(a/a)color(black)(i^2=(sqrt(-1))^2=-1)color(white)(a/a)|)))`

`rArr18-15i+3i^2=18-15i-3=15-15i`

`rArr(6-3i)(3-i)=15-15i`